tuberculosis WhiB1 does not respond to O2, which further supports the notion that SpiA is involved in the whcA-mediated stress response pathway. Collectively, our data suggest that the WhcA protein from C. glutamicum may function in a similar but unique fashion. Under normal growth conditions, SpiA may reduce apo-WhcA (S–S) to its holo form (Fe–S). During this process, the WhcA protein attains its Fe–S cluster, gains its ability to bind to DNA, and represses genes involved in oxidative stress response. However, under conditions of oxidative stress, the WhcA protein loses its Fe–S cluster, leading to the loss of its DNA-binding ability. Nevertheless,
Ganetespib nmr the DNA-binding activity of the WhcA protein has not yet been shown. To summarize, a regulatory model involving WhcA and SpiA is shown in Fig. 4. This work was supported by a National
Research Foundation grant (to H.-S. Lee) from the Korean Ministry of Education, Science and Technology (MEST 2010-0021994 Program of the NRF). “
“The metal-exporting systems CusCFBA of Escherichia coli and GesABC of Salmonella are resistance-nodulation-division (RND)-type this website multiprotein systems responsible for detoxification during metal stress. In this study, the substrate range was determined for each metal transport system and possible amino acid residues important in substrate specificity were identified. The Ges system, previously identified as a gold-efflux system, conferred resistance to the greatest number and variety of organic chemicals including chloramphenicol, not recognized previously as a substrate. Phylogenetic analysis showed that GesB is most closely related to a class of RND transporters including MexF that have been shown to be responsible for exporting fluoroquinolones, chloramphenicol, and biocides. However, many of the closest homologs of GesABC appear to play a role in metal resistance judging from the genetic context. In contrast, CusCFBA belongs to a distinct family
of RND-type monovalent metal-exporter systems containing a number pheromone of essential metal-binding methionines, resulting in a much narrower substrate range. Efflux is the most common widespread mechanism to regulate the concentration of a myriad of substances in all organisms. The substrate specificities of transporters vary widely and the mechanisms governing substrate recognition and subsequent transport are not well understood. Multiprotein complexes of the resistance-nodulation-division (RND) family in Gram-negative bacteria are both of medical and environmental importance. Within the genome of Escherichia coli, there are seven genes belonging to the RND family; acrB, acrD, acrF, cusA, mdtB, mdtC, and mdtF. Together with a membrane fusion protein (MFP) and an outer membrane factor (OMF), these inner membrane proteins form a complex responsible for the extrusion of a large variety of substrates mainly from the periplasm in a proton-gradient-dependent manner. The best-characterized member in E.