Molecular Microbiology

Cover image for Vol. 101 Issue 3

Early View (Online Version of Record published before inclusion in an issue)

Edited By: John D. Helmann

Impact Factor: 3.761

ISI Journal Citation Reports © Ranking: 2015: 32/123 (Microbiology); 86/289 (Biochemistry & Molecular Biology)

Online ISSN: 1365-2958

Associated Title(s): Cellular Microbiology


  1. 1 - 49
  1. Research Articles

    1. Cyclic di-AMP targets the cystathionine beta-synthase domain of the osmolyte transporter OpuC

      TuAnh Ngoc Huynh, Philip H. Choi, Kamakshi Sureka, Hannah E. Ledvina, Julian Campillo, Liang Tong and Joshua J. Woodward

      Version of Record online: 26 JUL 2016 | DOI: 10.1111/mmi.13456

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      Osmoadaptation is mediated in part through the uptake of the compatible solutes carnitine and betaine. Osmotolerance is inversely correlated with the production of the nucleotide c-di-AMP in Listeria monocytogenes, which directly binds to the CBS domain of the ATPase component of the carnitine transporter OpuC. These findings expand the link between c-di-AMP production and osmoadaptation among bacteria that produce this second messenger.

    2. GerM is required to assemble the basal platform of the SpoIIIA–SpoIIQ transenvelope complex during sporulation in Bacillus subtilis

      Christopher D. A. Rodrigues, Fernando H. Ramírez-Guadiana, Alexander J. Meeske, Xindan Wang and David Z. Rudner

      Version of Record online: 22 JUL 2016 | DOI: 10.1111/mmi.13457

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      During Bacillus subtilis sporulation a multimeric membrane complex connects the mother cell and developing spore. Assembly of this complex starts with a transenvelope interaction between SpoIIQ and SpoIIIAH. SpoIIQ anchors SpoIIIAH in the septum on the mother-cell side. How SpoIIQ is targeted to the forespore septal membranes has remained unclear. Here, we identify GerM as the missing factor that localizes SpoIIQ suggesting that these three proteins constitute the basal assembly platform for this complex.

    3. RpoS-dependent sRNA RgsA regulates Fis and AcpP in Pseudomonas aeruginosa

      Pei Lu, Yifei Wang, Yong Zhang, Yangbo Hu, Karl M. Thompson and Shiyun Chen

      Version of Record online: 22 JUL 2016 | DOI: 10.1111/mmi.13458

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      RgsA is a conserved sRNA in Pseudomonas species. Two direct regulatory targets of RgsA, the mRNAs coding for the global transcriptional regulator Fis and the acyl carrier protein AcpP, were identified in P. aeruginosa. RgsA downregulates the synthesis of Fis and AcpP by base-pairing, this regulation requires the RNA chaperone protein Hfq. Our study suggests a novel regulatory role of sRNA in which the versatile transcriptional regulator Fis and the stress regulator RpoS are connected by RgsA.

    4. You have full text access to this OnlineOpen article
      The bacterial SRP receptor, FtsY, is activated on binding to the translocon

      Albena Draycheva, Thomas Bornemann, Sergey Ryazanov, Nils-Alexander Lakomek and Wolfgang Wintermeyer

      Version of Record online: 19 JUL 2016 | DOI: 10.1111/mmi.13452

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      Cotranslational membrane targeting of ribosomes by the signal recognition particle (SRP) pathway in bacteria involves an interaction of the SRP protein Ffh and the SRP receptor, FtsY, through their homologous NG domains. SRP is activated on the ribosome by exposing the NG domain. Here we show that the activation for targeting complex formation is symmetric in that the NG domain of FtsY is exposed on binding to the translocon in a phospholipid environment.

    5. R-loop induced stress response by second (p)ppGpp synthetase in Mycobacterium smegmatis: functional and domain interdependence

      Sushma Krishnan, Anushya Petchiappan, Albel Singh, Apoorva Bhatt and Dipankar Chatterji

      Version of Record online: 19 JUL 2016 | DOI: 10.1111/mmi.13453

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      Due to the presence of a RNase HII domain and a (p)ppGpp synthesizing domain together in MS_RHII-RSD, R-loops are degraded, and the interrupted RNA polymerase is destabilized by unknown mechanism to rescue the organism from replicative stress. Consistent with this observation, MS_RHII-RSD gene expression was upregulated under ultra violet (UV) stress and increased R-loop accumulation was observed in this gene deleted strain. We have further elucidated its domain dependence for the optimal protein function.

    6. Functional compartmentalization of Rad9 and Hus1 reveals diverse assembly of the 9-1-1 complex components during the DNA damage response in Leishmania

      Jeziel D. Damasceno, Ricardo Obonaga, Elaine V. Santos, Alan Scott, Richard McCulloch and Luiz R. O. Tosi

      Version of Record online: 19 JUL 2016 | DOI: 10.1111/mmi.13441

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      The Rad9-Rad1-Hus1 (9-1-1) complex is a key component of the DNA metabolism in eukaryotes. The protozoan Leishmania express a 9-1-1-homolog clamp, which associate with chromatin and participate in the cellular response to genotoxic stress. LmRad9 and LmHus1-deficient cells have opposite phenotypes. Remarkably, LmRad9 forms an alternative complex, and LmHus1 exists as a monomer. These alternative forms may mediate the observed functional compartmentalization with a direct impact on the response to genotoxic stress.

    7. The genes that encode the gonococcal transferrin binding proteins, TbpB and TbpA, are differentially regulated by MisR under iron-replete and iron-depleted conditions

      Justin L. Kandler, Rosuany Vélez Acevedo, Mary Kathryne Dickinson, Devin R. Cash, William M. Shafer and Cynthia Nau Cornelissen

      Version of Record online: 18 JUL 2016 | DOI: 10.1111/mmi.13450

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      MisR regulates expression of the gonococcal genes that encode the transferrin-binding proteins (tbpA and tbpB). Phosphorylated MisR binds to the promoter of the tbp operon. The tbp genes are down-regulated by MisR under iron-replete conditions and up-regulated by MisR under iron-depleted conditions. This is the first demonstration that the gonococcal tbp genes are controlled by a trans-acting factor in addition to Fur.

    8. You have full text access to this OnlineOpen article
      Feedback control of Campylobacter jejuni flagellin levels through reciprocal binding of FliW to flagellin and the global regulator CsrA

      Katarzyna A. Radomska, Soledad R. Ordoñez, Marc M. S. M. Wösten, Jaap A. Wagenaar and Jos P. M. van Putten

      Version of Record online: 18 JUL 2016 | DOI: 10.1111/mmi.13455

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      We discovered a novel mechanism of regulation of flagellin biosynthesis in the bacterial pathogen Campylobacter jejuni. This mechanism controls flagellin levels through interaction of the flagellin assembly factor FliW with flagellin and the global post-transcriptional regulator CsrA.

    9. Overexpression of SepJ alters septal morphology and heterocyst pattern regulated by diffusible signals in Anabaena

      Vicente Mariscal, Dennis J. Nürnberg, Antonia Herrero, Conrad W. Mullineaux and Enrique Flores

      Version of Record online: 18 JUL 2016 | DOI: 10.1111/mmi.13436

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      Overexpression of septal protein SepJ in the filamentous, heterocyst-forming cyanobacterium Anabaena alters the structure of the intercellular septa and the heterocyst pattern regulated by the PatS morphogen and a HetN-related signal. The drawings show parts of a heterocyst and adjacent vegetative cell in wild-type Anabaena (upper panel) and the SepJ overexpressing strain (lower panel). Note the different sizes of the septum in the two strains and the possible presence of a higher number of SepJ-related septal junctions (red lines) in the SepJ overexpressing strain than in the wild type.

    10. Diphosphates at the 5′ end of the positive strand of yeast L-A double-stranded RNA virus as a molecular self-identity tag

      Tsutomu Fujimura and Rosa Esteban

      Version of Record online: 15 JUL 2016 | DOI: 10.1111/mmi.13446

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      The positive strand of the yeast L-A dsRNA viral genome has mostly 5′ diphosphates. These phosphates are not only essential for the cap-snatching reaction to synthesize capped viral mRNAs, but also crucial for viral transcription. Because host cytosolic RNAs (mRNA, tRNA, and rRNA) are uniformly devoid of 5′ pp-structures, the L-A virus takes advantage of its 5′ diphosphates, using them as a self-identity tag to propagate in the host cytoplasm.

    11. You have full text access to this OnlineOpen article
      Mutational analysis of the Aspergillus ambient pH receptor PalH underscores its potential as a target for antifungal compounds

      Daniel Lucena-Agell, América Hervás-Aguilar, Tatiana Múnera-Huertas, Olga Pougovkina, Joanna Rudnicka, Antonio Galindo, Joan Tilburn, Herbert N. Arst Jr and Miguel A. Peñalva

      Version of Record online: 15 JUL 2016 | DOI: 10.1111/mmi.13438

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      Fungi colonize environments with different values of pH by adapting their patterns of gene expression to the needs imposed by ambient pH. pH regulation is important for fungal pathogenicity, but therapeutically useful drugs targeting the pH signalling pathway are yet to be developed. We show that the ascomycete ambient pH receptor PalH resembles a major class of mammalian receptors, denoted GPCRs. Thus our data pave the way for the identification of specific inhibitors of the ambient pH receptor for antifungal intervention.

    12. Comprehensive analysis of type 1 fimbriae regulation in fimB-null strains from the multidrug resistant Escherichia coli ST131 clone

      Sohinee Sarkar, Leah W. Roberts, Minh-Duy Phan, Lendl Tan, Alvin W. Lo, Kate M. Peters, David L. Paterson, Mathew Upton, Glen C. Ulett, Scott A. Beatson, Makrina Totsika and Mark A. Schembri

      Version of Record online: 15 JUL 2016 | DOI: 10.1111/mmi.13442

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      Uropathogenic E. coli ST131 strains from the globally dominant fluoroquinolone-resistant subgroup possess an ISEc55 insertion in the fimB gene that regulates fimS, an invertible DNA element containing the type 1 fimbriae promoter. Using fimbrial expression assays and a novel Illumina-based read-mapping approach, we show that fimS inversion is reduced in these strains and controlled by other recombinases. The figure highlights differences in type 1 fimbriae regulation between reference ST131 (EC958) and non-ST131 (UTI89) strains.

    13. Global Tn-seq analysis of carbohydrate utilization and vertebrate infectivity of Borrelia burgdorferi

      Erin B. Troy, Tao Lin, Lihui Gao, David W. Lazinski, Maureen Lundt, Andrew Camilli, Steven J. Norris and Linden T. Hu

      Version of Record online: 15 JUL 2016 | DOI: 10.1111/mmi.13437

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      This work establishes Tn-seq as a new tool for performing high-throughput genetic fitness analyses in Borrelia burgdorferi. We used the technique to perform an in vitro screen exploring mechanisms of mannose, maltose, trehalose and N-acetyl-glucosamine metabolism in B. burgdorferi as well as a complementing in vivo screen in mice. In doing so we obtained insight into the potential functions of genes annotated as encoding carbohydrate transporters and an additional function of the response regulator Rrp1.

    14. Identification of the first transcriptional activator of an archaellum operon in a euryarchaeon

      Yan Ding, John Nash, Alison Berezuk, Cezar M. Khursigara, David N. Langelaan, Steven P. Smith and Ken F. Jarrell

      Version of Record online: 11 JUL 2016 | DOI: 10.1111/mmi.13444

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      Analysis of the complete genome sequence of a mutant of the archaeon Methanococcus maripaludis that had stopped production of components of archaella led to the identification of the first transcriptional activator, EarA, for the archaella operon in this major branch of Archaea. Cells deleted for earA do not transcribe the archaella operon and are nonarchaellated. Both in vitro and in vivo experiments demonstrate that EarA binds directly upstream of the promoter for the archaella operon.

    15. σE-dependent activation of RbpA controls transcription of the furA-katG operon in response to oxidative stress in mycobacteria

      Yangbo Hu, Zhongwei Wang, Lipeng Feng, Zhenkang Chen, Chunyou Mao, Yan Zhu and Shiyun Chen

      Version of Record online: 11 JUL 2016 | DOI: 10.1111/mmi.13449

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      The role of RbpA and its cooperation with σ factors in response to oxidative stress in mycobacteria are investigated, and the effect of RbpA activity in modulating the mycobacterial gene transcription profile under oxidative stress is characterized. We propose that, in the presence of H2O2, σE-dependent activation of RbpA interacts with the principal sigma factor σA and controls the transcription of katG, which encodes an H2O2 scavenging enzyme to decrease the H2O2 concentration in mycobacteria.

    16. More than a hole: the holin lethal function may be required to fully sensitize bacteria to the lytic action of canonical endolysins

      Sofia Fernandes and Carlos São-José

      Version of Record online: 11 JUL 2016 | DOI: 10.1111/mmi.13448

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      We show that bacterial cells under conditions supporting the membrane proton motive force (pmf) can counteract the lytic activity of canonical endolysins. Pmf dissipation by the holin or by ionophores mimicking its action results in drastic increase in endolysin lytic activity. Therefore, in canonical lysis the holin action may be crucial not only for endolysin transport to the cell wall, but also to turn bacteria fully susceptible to endolysin attack.

    17. Following transforming DNA in Helicobacter pylori from uptake to expression

      Christopher Corbinais, Aurélie Mathieu, Thierry Kortulewski, J. Pablo Radicella and Stéphanie Marsin

      Version of Record online: 8 JUL 2016 | DOI: 10.1111/mmi.13440

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      Helicobacter pylori, a major human pathogen at the origin of gastric ulcers and cancer, is characterised by its capacity to constitutively capture exogenous DNA and incorporate it into its genome. We have followed this process in real time by using fluorescently labelled DNA and its subsequent expression, confirming the role of ComEC for the transit of the DNA through the inner membrane.

    18. Trypanosomatid parasites rescue heme from endocytosed hemoglobin through lysosomal HRG transporters

      María Cabello-Donayre, Sophie Malagarie-Cazenave, Jenny Campos-Salinas, Francisco J. Gálvez, Alba Rodríguez-Martínez, Estela Pineda-Molina, Lina M. Orrego, Marta Martínez-García, María P. Sánchez-Cañete, Antonio M. Estévez and José M. Pérez-Victoria

      Version of Record online: 8 JUL 2016 | DOI: 10.1111/mmi.13430

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      An Achilles' heel of pathogenic trypanosomatid parasites is their absolute dependence on scavenging heme from their human hosts. Here, we unravel the mechanism used by Trypanosoma brucei (responsible for sleeping sickness) and Leishmania (leishmaniasis) to rescue heme from host hemoglobin. By using homologous and heterologous systems we show evidences strongly suggesting that parasite HRG transporters are responsible for heme transport from the endolysosomal compartment, where endocytosed hemoglobin is degraded, to the cytosol.

    19. A partial metabolic pathway enables group b streptococcus to overcome quinone deficiency in a host bacterial community

      Thierry Franza, Emilie Delavenne, Aurélie Derré-Bobillot, Vincent Juillard, Mylène Boulay, Emmanuelle Demey, Joelle Vinh, Gilles Lamberet and Philippe Gaudu

      Version of Record online: 8 JUL 2016 | DOI: 10.1111/mmi.13447

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      Group B Streptococcus (GBS) is a human commensal bacterium that can become a pathogen. In polymicrobial population, GBS is able to acquire 1,4-dihydroxy-2-naphthoic acid (DHNA) and use it to synthesize its own demethylmenaquinones (DMKs) by the IspB and MenA enzymes. DMKs are substrates of the CydAB oxidase that also requires oxygen and exogenous heme to be active. Thus, through interspecies metabolic exchanges, GBS is able to switch from fermentation towards a respiratory metabolism that increases its growth capacity and virulence in the host.

    20. Acidic pH sensing in the bacterial cytoplasm is required for Salmonella virulence

      Jeongjoon Choi and Eduardo A. Groisman

      Version of Record online: 8 JUL 2016 | DOI: 10.1111/mmi.13439

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      How does an organism respond to changes in the pH of its surroundings? We now report that the sensor PhoQ from Salmonella enterica operates as a cytoplasmic pH sensor, and that its ability to sense a decrease in cytoplasmic pH is necessary for Salmonella virulence. By responding to cytoplasmic pH changes PhoQ enables S. enterica to integrate host and bacterial metabolic signals to activate a critical virulence program.

    21. Structural organization of membrane-inserted hexamers formed by Helicobacter pylori VacA toxin

      Tasia M. Pyburn, Nora J. Foegeding, Christian González-Rivera, Nathan A. McDonald, Kathleen L. Gould, Timothy L. Cover and Melanie D. Ohi

      Version of Record online: 8 JUL 2016 | DOI: 10.1111/mmi.13443

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      Helicobacter pylori colonizes the stomach and increases the risk of gastroduodenal disease in infected individuals. H. pylori VacA, a secreted toxin, forms channels in cell membranes and causes alterations in host cells. The vacA genotype of a strain correlates with the risk of H. pylori-associated gastric cancer and the various forms of VacA have different activities in vitro. We show that upon binding to membrane, monomeric VacA oligomerizes into membrane-inserted hexamers. There is a visible structural difference in the pore-forming domain of VacA when comparing soluble and membrane-bound hexamers. These results provide important new insights into mechanisms of VacA oligomerization and membrane insertion.

    22. The crystal structure of the major pneumococcal autolysin LytA in complex with a large peptidoglycan fragment reveals the pivotal role of glycans for lytic activity

      Tatyana Sandalova, Mijoon Lee, Birgitta Henriques-Normark, Dusan Hesek, Shahriar Mobashery, Peter Mellroth and Adnane Achour

      Version of Record online: 5 JUL 2016 | DOI: 10.1111/mmi.13435

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      The atomic resolution crystal structure of the S. pneumonia-associated major autolysin LytA in complex with a large peptidoglycan fragment allows for precise determination of the conformation of the substrate as well as for a thorough investigation of the role of twenty-one substrate-interacting residues within the binding crevice. The present study demonstrates that several glycan-interacting residues located outside the catalytic site play nonetheless a critical role in the lytic activity of this key bacterial enzyme.

    23. Pseudopilin residue E5 is essential for recruitment by the type 2 secretion system assembly platform

      Mangayarkarasi Nivaskumar, Javier Santos-Moreno, Christian Malosse, Nathalie Nadeau, Julia Chamot-Rooke, Guy Tran Van Nhieu and Olivera Francetic

      Version of Record online: 5 JUL 2016 | DOI: 10.1111/mmi.13432

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      The highly conserved Glu residue at position 5 (E5) in the transmembrane segments of T2SS pseudopilins and type 4 pilins is essential for fibre assembly and function. Using the bacterial two-hybrid and copurification approaches, we show that the major T2SS pseudopilin and one of four minor pseudopilins interact with the assembly platform components PulM and PulF. Residue E5 is specifically required for interactions with PulM, suggesting a role in pseudopilin recruitment to the assembly complex.

    24. Identification and functional analysis of two toxin–antitoxin systems in Campylobacter jejuni

      Zhangqi Shen, Rocky D. Patil, Orhan Sahin, Zuowei Wu, Xiao-Ying Pu, Lei Dai, Paul J. Plummer, Michael J. Yaeger and Qijing Zhang

      Version of Record online: 4 JUL 2016 | DOI: 10.1111/mmi.13431

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      Campylobacter jejuni is a major zoonotic pathogen. Here we present the first identification of toxin-antitoxin (TA) systems in this organism, which play an important role in maintaining the stability of virulence plasmid pVir. Both toxins are proteic and inhibit cell growth by degrading cellular mRNA. Antitoxin VirA neutralizes toxin VirT by protein-protein interaction, while antitoxin cjrA detoxifies toxin CjpT by binding to its mRNA.

    25. The LysR-type transcriptional regulator, CidR, regulates stationary phase cell death in Staphylococcus aureus

      Sujata S. Chaudhari, Vinai C. Thomas, Marat R. Sadykov, Jeffrey L. Bose, Daniel J. Ahn, Matthew C. Zimmerman and Kenneth W. Bayles

      Version of Record online: 4 JUL 2016 | DOI: 10.1111/mmi.13433

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      Within a developing bacterial biofilm, a subpopulation of cells undergoes cell death and release critical biofilm matrix components. Interference of such homeostatic bacterial death mechanisms hinders biofilm maturation and thus represents a potential therapeutic target. Here, we elucidate the role of various members of the CidR regulon in controlling cell death in staphylococcal populations. Notably, we demonstrate that two integral membrane proteins, CidA and CidB antithetically regulate cell death by modulating intracellular carbon partitioning into acetate and acetoin generating pathways.

  2. MicroReview

    1. You have free access to this content
      Non-canonical roles of tRNAs and tRNA mimics in bacterial cell biology

      Assaf Katz, Sara Elgamal, Andrei Rajkovic and Michael Ibba

      Version of Record online: 28 JUN 2016 | DOI: 10.1111/mmi.13419

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      The main function of tRNAs is usually considered to be the transfer of activated amino acids from aminoacyl-tRNA synthetases to nascent peptides at the ribosome. Consequentially, tRNAs are considered essential in the evolution of organisms that use proteins instead of RNAs as enzymes. Nevertheless, tRNAs also have several functions beyond translation. Here we discuss how tRNAs were coopted from main in translation role into other metabolic, regulatory and genomic functions.

  3. Research Articles

    1. RflM mediates target specificity of the RcsCDB phosphorelay system for transcriptional repression of flagellar synthesis in Salmonella enterica

      Caroline Kühne, Hanna M. Singer, Eva Grabisch, Luca Codutti, Teresa Carlomagno, Andrea Scrima and Marc Erhardt

      Version of Record online: 27 JUN 2016 | DOI: 10.1111/mmi.13427

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      In Salmonella, biosynthesis of flagella is subject to strict regulatory control. A novel flagellar-specific auxiliary protein, RflM, mediates target specificity of the global RcsCDB phosphorelay system for repression of the flagellar master regulator operon, flhDC. The coordinated action of the flagellar-dependent regulator RflM and the global Rcs system allows Salmonella to fine-tune the initiation of flagellar synthesis in response to diverse environmental conditions.

    2. ThrR, a DNA-binding transcription factor involved in controlling threonine biosynthesis in Bacillus subtilis

      Jonathan Rosenberg, Peter Müller, Sabine Lentes, Martin J. Thiele, Daniel R. Zeigler, Dominik Tödter, Henry Paulus, Sabine Brantl, Jörg Stülke and Fabian M. Commichau

      Version of Record online: 27 JUN 2016 | DOI: 10.1111/mmi.13429

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      Biosynthesis of the amino acid threonine is complex and involves several enzymatic reactions in the Gram-positive model bacterium Bacillus subtilis. Here we describe the identification of ThrR, a DNA-binding transcription factor that controls threonine biosynthesis in B. subtilis. ThrR orthologs are ubiquitous in the genomes from the Gram-positive phylum Firmicutes and in some Gram-negative bacteria.

    3. The perilipin-like PPE15 protein in Mycobacterium tuberculosis is required for triacylglycerol accumulation under dormancy-inducing conditions

      Jaiyanth Daniel, Nidhi Kapoor, Tatiana Sirakova, Rajesh Sinha and Pappachan Kolattukudy

      Version of Record online: 21 JUN 2016 | DOI: 10.1111/mmi.13422

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      Triacylglycerol accumulation inside Mycobacterium tuberculosis is associated with its entry into a drug-tolerant, dormant state. The mycobacterial ppe15 gene is shown in this study to be essential for the accumulation of lipid droplets under dormancy-inducing conditions. Deletion of the ppe15 gene diminished the ability of the pathogen to accumulate triacylglycerol in lipid droplets and decreased its ability to develop phenotypic tolerance to rifampicin in the multiple-stress and in vitro granuloma models of dormancy.

    4. RNase E-based degradosome modulates polyadenylation of mRNAs after Rho-independent transcription terminators in Escherichia coli

      Kristen B. Mildenhall, Nicholas Wiese, Daewhan Chung, Valerie F. Maples, Bijoy K. Mohanty and Sidney R. Kushner

      Version of Record online: 16 JUN 2016 | DOI: 10.1111/mmi.13413

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      In Escherichia coli both poly(A) polymerase I (PAP I) and polynucleotide phosphorylase (PNPase) can add nucleotides to the 3′ termini of a variety of RNA molecules (mRNAs, rRNAs, tRNAs and sRNAs). However, the addition of poly(A) tails by PAP I after Rho-independent transcription terminators, surprisingly, requires both an intact RNase E-based degradosome and a functional PNPase protein.

    5. Elucidation of a mechanism of oxidative stress regulation in Francisella tularensis live vaccine strain

      Zhuo Ma, Vincenzo C. Russo, Seham M. Rabadi, Yu Jen, Sally V. Catlett, Chandra Shekhar Bakshi and Meenakshi Malik

      Version of Record online: 16 JUN 2016 | DOI: 10.1111/mmi.13426

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      Francisella tularensis is a highly virulent human pathogen. The mechanism of regulation of the oxidative stress response that facilitates the survival of F. tularensis in phagocytic cells is not known. This study characterized the role of an oxidative stress regulator, OxyR, in F. tularensis LVS. The results demonstrate that OxyR is an important virulence factor and transcriptional regulator of the oxidative stress response of F. tularensis.

  4. MicroReview

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      Interplay of regulatory RNAs and mobile genetic elements in enteric pathogens

      Kathrin S. Fröhlich and Kai Papenfort

      Version of Record online: 16 JUN 2016 | DOI: 10.1111/mmi.13428

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      Abbreviated Summary

      Small, regulatory RNAs (sRNAs) serve important roles in bacterial gene regulation. Frequently, sRNAs also function as key players in the interaction of core genome elements and horizontally-acquired DNA. This MicroReview focuses on sRNAs functioning between existing and newly obtained genetic material in enterobacterial pathogens.

  5. Research Articles

    1. Integration host factor and LuxR synergistically bind DNA to coactivate quorum-sensing genes in Vibrio harveyi

      Ryan R. Chaparian, Stephen G. Olney, Christine M. Hustmyer, Dean A. Rowe-Magnus and Julia C. van Kessel

      Version of Record online: 16 JUN 2016 | DOI: 10.1111/mmi.13425

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      The bacterial communication system called quorum sensing controls group behaviors in Vibrio harveyi through the master transcription factor LuxR. LuxR directly interacts with Integration Host Factor (IHF), a nucleoid-associated protein and global transcription regulator, and LuxR and IHF coregulate 118 genes. LuxR and IHF synergistically bind DNA to control the timing and level of expression of quorum-sensing genes, including the bioluminescence and osmotic stress response genes.

    2. You have full text access to this OnlineOpen article
      Evolved plasmid-host interactions reduce plasmid interference cost

      Hirokazu Yano, Katarznya Wegrzyn, Wesley Loftie-Eaton, Jenny Johnson, Gail E. Deckert, Linda M. Rogers, Igor Konieczny and Eva M. Top

      Version of Record online: 15 JUN 2016 | DOI: 10.1111/mmi.13407

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      The molecular mechanisms by which a broad-host-range antibiotic resistance plasmid can adapt to a novel bacterial host and increase its persistence were investigated using experimentally evolved plasmids. These evolved plasmids encode a modified replication initiation protein that simultaneously increases plasmid copy number and decreases interference cost by decreasing binding affinity to the host helicase (DnaB). This in turn causes plasmid replication to be dependent on host DnaA, an example of host specialization.

    3. L-fucose influences chemotaxis and biofilm formation in Campylobacter jejuni

      Ritika Dwivedi, Harald Nothaft, Jolene Garber, Lin Xin Kin, Martin Stahl, Annika Flint, Arnoud H. M. van Vliet, Alain Stintzi and Christine M. Szymanski

      Version of Record online: 10 JUN 2016 | DOI: 10.1111/mmi.13409

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      The influence of fucose availability on C. jejuni chemotaxis and biofilm formation was investigated. Wildtype (WT) C. jejuni forms biofilms when nutrients are limited, but swims towards L-fucose (blue ovals) and exhibits enhanced growth and reduced biofilms in its presence. Disruption of fucose uptake through mutation of the permease, fucP, results in biofilm formation even though chemotaxis is not affected. The putative dehydrogenase mutant, cj0485, abolishes both phenotypes suggesting a key role in fucose chemotaxis.

    4. A response regulator promotes Francisella tularensis intramacrophage growth by repressing an anti-virulence factor

      Kathryn M. Ramsey and Simon L. Dove

      Version of Record online: 10 JUN 2016 | DOI: 10.1111/mmi.13418

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      It was thought that the response regulator PmrA was essential for the intramacrophage growth of Francisella tularensis because it positively regulated the expression of type VI secretion genes present on the so-called Francisella Pathogenicity Island. We show instead that PmrA promotes intramacrophage growth by repressing a gene that encodes a previously unknown anti-virulence factor. This PmrA-repressed gene is the first F. tularensis gene we are aware of that can interfere with intramacrophage growth and survival.

  6. MicroReviews

    1. The magic dance of the alarmones (p)ppGpp

      Wieland Steinchen and Gert Bange

      Version of Record online: 10 JUN 2016 | DOI: 10.1111/mmi.13412

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      The alarmones (p)ppGpp are essential second messengers conserved among bacteria and the plant chloroplasts. This review discusses the molecular plasticity of enzymes and targets involved in (p)ppGpp metabolism and regulation, respectively.

  7. Research Articles

    1. Function, expression, specificity, diversity and incompatibility of actinobacteriophage parABS systems

      Rebekah M. Dedrick, Travis N. Mavrich, Wei L. Ng, Juan C. Cervantes Reyes, Matthew R. Olm, Rachael E. Rush, Deborah Jacobs-Sera, Daniel A. Russell and Graham F. Hatfull

      Version of Record online: 10 JUN 2016 | DOI: 10.1111/mmi.13414

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      Over 40 completely sequenced temperate actinobacteriophages encode diverse Type Ib partitioning cassettes containing parA and parB genes as well as centromere-like sites parS-L and parS-R. Their prophages replicate extrachromosomally at low copy number and the partitioning systems mediate prophage maintenance, although related phages exhibit lysogenic incompatibility through competition of ParB binding to the parS sites.

    2. Molybdate uptake by Agrobacterium tumefaciens correlates with the cellular molybdenum cofactor status

      Marie-Christine Hoffmann, Koral Ali, Marleen Sonnenschein, Laura Robrahn, Daria Strauss, Franz Narberhaus and Bernd Masepohl

      Version of Record online: 10 JUN 2016 | DOI: 10.1111/mmi.13421

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      Most bacteria synthesize high-affinity molybdate (Mo) transporters, ModABC, under Mo-limiting conditions. Under Mo-replete conditions, modABC transcription is repressed by molybdate-binding ModE regulators in Escherichia coli and other bacteria. Here, we characterized a ModE regulator lacking a molybdate-binding domain (ModES) from Agrobacterium tumefaciens. We provide first evidence that modABC repression requires the molybdenum cofactor, Moco, rather than directly responding to molybdate in A. tumefaciens and possibly also in other species lacking a full-length ModE regulator.

    3. The function of the PduJ microcompartment shell protein is determined by the genomic position of its encoding gene

      Chiranjit Chowdhury, Sunny Chun, Michael R. Sawaya, Todd O. Yeates and Thomas A Bobik

      Version of Record online: 7 JUN 2016 | DOI: 10.1111/mmi.13423

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      Abbreviated Summary

      Deletion of the pduA gene impairs the function of the 1,2-propanediol utilization microcompartment of Salmonella (Pdu MCP). When PduJ (a close homologue of PduA) is expressed from plasmid, it does not correct the defects of a ΔpduA mutant. However, when PduJ is expressed from the pduA chromosomal locus, it restores normal MCP function. Thus, we propose that the function of the pduJ gene is dependent on the genomic position of its encoding gene.

    4. Glucose induces delocalization of a flagellar biosynthesis protein from the flagellated pole

      Soyoung Park, Young-Ha Park, Chang-Ro Lee, Yeon-Ran Kim and Yeong-Jae Seok

      Version of Record online: 3 JUN 2016 | DOI: 10.1111/mmi.13424

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      Abbreviated Summary

      Making a right decision to stay or move is critical for survival in a changing environment. Here we identify a novel mechanism for glucose-dependent on-off switching of flagellar synthesis in Vibrio vulnificus: When enzyme IIAGlc of the bacterial PEP:carbohydrate phosphotransferase system is dephosphorylated in the presence glucose, it delocalizes a protein required for flagellar biosynthesis from the flagellated pole. This leads to a loss of motility and enables bacteria to stay in a favorable habitat.

    5. The Saccharomyces cerevisiae Ptc1 protein phosphatase attenuates G2-M cell cycle blockage caused by activation of the cell wall integrity pathway

      Laura Tatjer, Asier González, Albert Serra-Cardona, Anna Barceló, Antonio Casamayor and Joaquín Ariño

      Version of Record online: 3 JUN 2016 | DOI: 10.1111/mmi.13416

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      Activation of the cell wall integrity pathway leads to phosphorylation of Cdc28 and delay in cell cycle progression at the G2-M transition. By dephosphorylating and inhibiting the MAPK kinase Mkk1, the Ptc1 phosphatase avoids excessive activation of the Sl2 MAPK and contributes to resume cell cycle.

    6. Rearrangements of α-helical structures of FlgN chaperone control the binding affinity for its cognate substrates during flagellar type III export

      Miki Kinoshita, Yuki Nakanishi, Yukio Furukawa, Keiichi Namba, Katsumi Imada and Tohru Minamino

      Version of Record online: 3 JUN 2016 | DOI: 10.1111/mmi.13415

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      The structure and structure-based functional analyses reveal that the N-loop between α1 and α2 of FlgN acts as a structural switch for the rearrangement of three α helices to control the binding affinity of helix α3 for FlgK.

    7. Structural insights into the inhibition mechanism of bacterial toxin LsoA by bacteriophage antitoxin Dmd

      Hua Wan, Yuichi Otsuka, Zeng-Qiang Gao, Yong Wei, Zhen Chen, Michiaki Masuda, Tetsuro Yonesaki, Heng Zhang and Yu-Hui Dong

      Version of Record online: 2 JUN 2016 | DOI: 10.1111/mmi.13420

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      The antitoxin Dmd from T4 phage is inserted into the deep groove between the N-terminal repeated domain (NRD) and the Dmd-binding domain (DBD) of Escherichia coli toxin LsoA. The conserved Dmd-interacting residues in this groove are vital for LsoA toxicity generated by its RNase activity. Therefore, Dmd can recognize LsoA and inhibit its toxicity by occupying the active site via substrate RNA mimicry.

    8. A protein complex supports the production of Spo0A-P and plays additional roles for biofilms and the K-state in Bacillus subtilis

      Eugenie J. Dubnau, Valerie J. Carabetta, Andrew W. Tanner, Mathieu Miras, Christine Diethmaier and David Dubnau

      Version of Record online: 2 JUN 2016 | DOI: 10.1111/mmi.13411

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      In Bacillus subtilis, the proteins YlbF, YmcA and YaaT form a complex needed for the formation of biofilms, for sporulation and for genetic transformation. This paper strongly supports a role for these proteins in stimulating the phosphorylation of the key transcription factor, Spo0A. The present data contradict an alternative published model that proposed a role for the complex in destabilizing the mRNA for SinR, a repressor of biofilm formation.

    9. You have full text access to this OnlineOpen article
      Base J represses genes at the end of polycistronic gene clusters in Leishmania major by promoting RNAP II termination

      David L. Reynolds, Brigitte T. Hofmeister, Laura Cliffe, T. Nicolai Siegel, Britta A. Anderson, Stephen M. Beverley, Robert J. Schmitz and Robert Sabatini

      Version of Record online: 1 JUN 2016 | DOI: 10.1111/mmi.13408

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      Base J regulates gene expression by stimulating premature termination within gene clusters in Leishmania major. Loss of base J within gene clusters leads to read through transcription and upregulation of genes downstream of base J. The loss of base J at the end of gene clusters results in read through transcription into the opposing gene clusters. However, transcription of the opposing DNA strand has no effect on mRNA levels from the sense strand.

    10. A scaffold protein connects type IV pili with the Chp chemosensory system to mediate activation of virulence signaling in Pseudomonas aeruginosa

      Yuki F. Inclan, Alexandre Persat, Alexander Greninger, John Von Dollen, Jeffery Johnson, Nevan Krogan, Zemer Gitai and Joanne N. Engel

      Version of Record online: 27 MAY 2016 | DOI: 10.1111/mmi.13410

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      Type IV pili (TFP) function as mechanosensors to trigger acute virulence programs in Pseudomonas aeruginosa by signaling through the Chp chemosensory system. We show that FimL, a Chp chemosensory system accessory protein of unknown function, acts as a scaffold to enable spatial colocalization of TFP and Chp system components to coordinate cAMP-dependent transcription of virulence genes upon surface contact. These components are found in other TFP-expressing bacteria, suggesting that mechanochemical surface sensing may be widespread.

    11. SilE is an intrinsically disordered periplasmic “molecular sponge” involved in bacterial silver resistance

      Karishma R. Asiani, Huw Williams, Louise Bird, Matthew Jenner, Mark S. Searle, Jon L. Hobman., David J. Scott and Panos Soultanas

      Version of Record online: 7 MAY 2016 | DOI: 10.1111/mmi.13399

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      We show that the periplasmic SilE protein, which is part of the silver resistance machinery of Escherichia coli, is an intrinsically disordered protein in its apo-form and folds to a holo-form upon binding to Ag+ ions. Maximal folding is induced upon binding to six Ag+ ions but each holo-SilE molecule can bind up to eight Ag+ ions. Coordination of Ag+ ions is mediated via conserved histidine and methionine residues arranged in two characteristic motifs (MxxHxxxxxxHxxMxx and HxxMxxxHxxMxx). SilE may act as a metal-ion chaperone to transport Ag+ ions to the SilABC transporter and/or signal via the histidine kinase sensor SilS to activate the remainder of the silver resistance machinery.

    12. Listeria monocytogenes wall teichoic acid decoration in virulence and cell-to-cell spread

      Patricia A. Spears, Edward A. Havell, Terri S. Hamrick, John B. Goforth, Alexandra L. Levine, S. Thomas Abraham, Christian Heiss, Parastoo Azadi and Paul E. Orndorff

      Version of Record online: 10 MAR 2016 | DOI: 10.1111/mmi.13353

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      Phage resistant (ΦR) Listeria monocytogenes mutants (green) exhibit short actin tails (red) during cytosolic growth, and spread cell-to-cell poorly compared to the parent. Phage resistance was associated with the absence of a single decorating sugar (galactose) on wall teichoic acid (WTA). The mutants were additionally dramatically attenuated in a mouse oral infection model. A hypothetical pathway for WTA galactosylation is proposed.


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