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January 30, 2014
Very Important Papers:
Active Efflux Influences the Potency of Quorum-Sensing Inhibitors in Pseudomonas aeruginosa
Joseph D. Moore, Joseph P. Gerdt, Nora R. Eibergen, and Helen E. Blackwell*
Small molecules capable of inhibiting bacterial cell--cell signaling, or quorum sensing (QS), are of significant interest as new chemical tools and potential anti-infective agents. Gram-negative bacteria predominately use N-acyl L-homoserine lactone (AHL) signals for QS. Now, Helen E. Blackwell (University of Wisconsin) and co-workers have shown that a variety of AHL-derived QS inhibitors in the pathogen Pseudomonas aeruginosa are substrates of its MexAB-OprM drug-efflux pump. In contrast, an aminobenzimidazole-type QS inhibitor does not display this efflux-induced reduction in potency. These results suggest that active efflux will need to be considered in the design of new QS modulators in P. aeruginosa and other bacteria.
Catalytic Scope of the Thiamine-Dependent Multifunctional Enzyme Cyclohexane-1,2-dione Hydrolase
Sabrina Loschonsky, Simon Waltzer, Sonja Fraas, Tobias Wacker, Susana L. A. Andrade, Peter M. H. Kroneck, and Michael Müller*
Cyclohexane-1,2-dione hydrolase (CDH) is a thiamine diphosphate-dependent enzyme that can accept a number of aromatic aldehydes that were previously hard to convert. Now, Michael Müller (Universität Freiburg) and co-workers have expressed CDH in E. coli and the recombinant CDH showed the same C–C bond-cleavage and C–C bond-formation activities as the wild-type enzyme. Furthermore, CDH catalyzes the asymmetric cross-benzoin reaction of aromatic aldehydes and pyruvate, up to quantitative conversion and 92–99% ee. On a semipreparative scale, the sterically demanding substrates 4-(tert-butyl)benzaldehyde and 2-naphthaldehyde, respectively, were transformed into the corresponding 2-hydroxyketone products in high yields. Additionally, certain benzaldehydes with electron-withdrawing substituents were identified as potential inhibitors of the C–C bond-formation activity of CDH. In a related paper, published simultaneously in ChemCatChem, M. Müller and co-workers also characterized the ability of CDH to catalyze the enantio-selective formation of (S)-acetoin by homocoupling of pyruvate, homocoupling of acetaldehyde, and cross-coupling of pyruvate and acetaldehyde.
Recently Published Articles
- Synthesis of a Glycopeptide Vaccine Conjugate for Induction of Antibodies Recognizing O-Mannosyl Glycopeptides
MSc Jin Yu and Dr. Ulrika Westerlind
Article first published online: 17 APR 2014 | DOI: 10.1002/cbic.201300537
Sugars from the brain: The chemical synthesis and immunization of a glycopeptide vaccine construct containing the common O-mannose motif Galβ1-4GlcNAcβ1-2ManαThr was accomplished to generate antibody-based tools for enrichment, detection, and identification of mammalian O-mannosyl glycoproteins and glycopeptides.
- Exosomes and Microvesicles: Identification and Targeting By Particle Size and Lipid Chemical Probes
Noah Kastelowitz and Prof. Dr. Hang Yin
Article first published online: 16 APR 2014 | DOI: 10.1002/cbic.201400043
Targeting extracellular vesicles: Exosomes and microvesicles are submicroscopic vesicles released by cells into the extracellular space that play important signaling roles in normal and pathophysiologic processes. We highlight current methods to detect these vesicles and focus on potential future applications of lipid chemical probes to target these vesicles.
- Structural Basis of Furan–Amino Acid Recognition by a Polyspecific Aminoacyl-tRNA-Synthetase and its Genetic Encoding in Human Cells
Moritz J. Schmidt, Annemarie Weber, Moritz Pott, Prof. Wolfram Welte and Dr. Daniel Summerer
Article first published online: 15 APR 2014 | DOI: 10.1002/cbic.201402006
Photo opportunity: We report the genetic encoding of a furan-based, photo-crosslinking amino acid in human cells by a mutant pyrrolysyl-tRNA synthetase (PylRS) with broad polyspecificity. Crystal structures of this enzyme reveal the mode of furan amino acid recognition and the basis of polyspecificity, thus providing a promising starting point for engineering PylRS mutants with increased substrate scope.
- A New Bifunctional Chelator Enables Facile Biocoupling and Radiolabeling as the Basis for a Bioconjugation Kit
Dr. Ali Barandov, Dr. Dan Grünstein, Dr. Ivalaya Apostolova, Dr. Ralph Buchert, Michel Roger, Prof. Dr. Winfried Brenner, Prof. Dr. Ulrich Abram and Prof. Dr. Peter H. Seeberger
Article first published online: 10 APR 2014 | DOI: 10.1002/cbic.201400001
Bioconjugation kit: We present a facile biocoupling approach using a new tridendate bifunctional chelator that enables synthesis of glycoconjugates in a single step with high yields and short preparation time. Radiolabeled carbohydrates were achieved in both pre- and postlabeling fashion by using this approach.
- Cellular Scent of Influenza Virus Infection.
Dr. Alexander A. Aksenov, Christian E. Sandrock, Dr. Weixiang Zhao, Shankar Sankaran, Michael Schivo, Richart Harper, Dr. Carol J. Cardona, Dr. Zheng Xing and Dr. Cristina E. Davis
Article first published online: 9 APR 2014 | DOI: 10.1002/cbic.201300695
A case of sniffles: The composition of volatile organic compounds (VOCs) in human breath changes under disease conditions, including viral infection. The VOC profiles upon infection with three influenza virus strains were assayed in a cell line. Diagnostic devices based on VOC analysis have enormous potential in the clinical setting.