Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
June 14, 2013
ChemBioChem 9/2013 Fine-tuning protein stability
Rubini and co-workers have created a thioredoxin analogue (Trx1P) containing a single cis-proline residue by replacing the trans-proline residues with alanine. In their Communication, the authors show that the non-natural amino acids (2S,4R)- and (2S,4S)-fluoroproline ((4R)-Flp and (4S)-Flp) could be quantitatively incorporated into Trx1P. An endo conformation of the Pro pyrrolidine ring was found in both fluoroproline stereoisomers, although (4R)-Flp usually favors the exo conformation. This indicates that the tertiary structure directs the Flp ring conformation and the Pro-to-Flp substitutions give the potential for modulating the stability of proteins without changing their biological activity.
In another Communication, Bhabak et al. describe two complimentary doubly labeled ceramides, each of them carrying 7-nitrobenz-2-oxa-1,3-diazole (NBD) as donor and Nile Red (NR) as acceptor fluorophores. Both substrates were treated with acid and neutral ceramidases and shown to be effective FRET probes for the real-time determination of ceramidase activity. The ceramide analogue with NBD attached to the fatty acid moiety and NR to the sphingosine part showed larger spectral changes and has the potential to be used as an in situ probe in living cells.
Aurachin RE, first identified in the genus Rhodococcus, is a farnesylated quinoline antibiotic active against other Gram-positive bacteria. Now, in a Full Paper, Kitagawa et al. present the heterologous expression of the gene cluster controlling aurachin RE biosynthesis. This cluster contains genes that encode, among others, a prenyltransferase, polyketide synthase, and notably, a cytochrome P450 (RauA). Disruption of the rauA gene led to accumulation of an aurachin lacking the N-hydroxyl group that is crucial for antibacterial activity. Identification of this P450 suggests a convergent evolution of unrelated Stigametlla species that instead use a Rieske oxygenase to produce aurachins.
This issue also contains, among others, notable contributions from Nicola Brasch (Kent State University), Christy Landes (Rice University) and R. Jeremy Johnson (Butler University). Browse Issue 9/2013 now.
Recently Published Articles
- Dual Activators of Protein Kinase R (PKR) and Protein Kinase R-Like Kinase (PERK) Identify Common and Divergent Catalytic Targets
Huijun Bai, Dr. Ting Chen, Dr. Jie Ming, Prof. Hong Sun, Peng Cao, Dr. Dahlene N. Fusco, Prof. Raymond T. Chung, Prof. Michael Chorev, Prof. Qi Jin and Prof. Bertal H. Aktas
Article first published online: 19 JUN 2013 | DOI: 10.1002/cbic.201300177
The jobs of the PERK? DHBDC, a dual activator of two eIF2α kinases, PKR and PERK, has been identified by chemical genetics approaches. DHBDC induces eIF2α phosphorylation and its downstream effectors by activating PKR and PERK, and activates the NF-κB pathway exclusively through PERK.
- Fluorescent THF-Based Fructose Analogue Exhibits Fructose-Dependent Uptake
Dr. Marina Tanasova, Matthew Plutschack, Megan E. Muroski, Prof. Shana J. Sturla, Prof. Geoffrey F. Strouse and Prof. D. Tyler McQuade
Article first published online: 19 JUN 2013 | DOI: 10.1002/cbic.201300164
Differentiating cancer cells: To answer the controversial question, “What role does fructose play in human health?”, the mechanism of fructose transport must be understood. One path to this understanding is the creation of specific probes. This work describes the synthesis and use of a 2,5-anhydro-D-mannitol-based fluorescent probe to target the fructose-specific transporters.
- A Computational Study of the Effects of 13C–13C Scalar Couplings on 13C CEST NMR Spectra: Towards Studies on a Uniformly 13C-Labeled Protein
Dr. Pramodh Vallurupalli, Dr. Guillaume Bouvignies and Prof. Lewis E. Kay
Article first published online: 19 JUN 2013 | DOI: 10.1002/cbic.201300230
Read the label: The NMR CEST experiment can be used to reconstruct spectra of sparsely populated, transiently formed protein conformers so long as they exchange with a highly populated ground state with rates of 20–300 s−1. Here we establish that accurate 13C chemical shifts of side-chain carbon nuclei can be obtained from uniformly 13C-labeled samples, without interference from the coupled 13C spin network.
- Development of Colorimetric HTS Assay of Cytochrome P450 for ortho-Specific Hydroxylation, and Engineering of CYP102D1 with Enhanced Catalytic Activity and Regioselectivity
Dr. Kwon-Young Choi, Eun-Ok Jung, Prof. Dr. Hyungdon Yun, Prof. Dr. Yung-Hun Yang, Prof. Dr. Romas J. Kazlauskas and Prof. Dr. Byung-Gee Kim
Article first published online: 18 JUN 2013 | DOI: 10.1002/cbic.201300212
High-speed activity: A general HTS assay method for ortho-specific hydroxylation by P450 enzymes is presented. In order to screen for P450 variants with higher hydroxylation activities, an indirect HTS assay method to sense aldehyde molecules generated from O-dealkylation reaction of chemically permethylated substrate was developed.
- Chemical Tools for Studying the Biological Function of Glycolipids
Dr. Bridget L. Stocker and Dr. Mattie S. M. Timmer
Article first published online: 18 JUN 2013 | DOI: 10.1002/cbic.201300064
Comprehensive toolkit: The vital roles played by glycolipids in many biological systems have led synthetic chemists to develop unique chemical tools that can be used to help to understand glycolipids' activities. We highlight approaches that have been made in the development of glycolipid probes, including both recent and historical examples of a variety of probe types.