Tivities cooperatively with the Suf system. Transcriptional data on erpA and tauD expression changes for -Fe vs. +Fe growth conditions are not available. Mammalian hosts starve Y. pestis of iron and, therefore, the Suf complex constitutes a good target for inhibitory drug design.Pieper et al. BMC Microbiology 2010, 10:30 http://www.biomedcentral.com/1471-2180/10/Page 19 ofEnzymes with Fe-S clusters in their catalytic cores, many of them in the TCA cycle, are also displayed in Figure 5. Although in different ratios, subunits of such PD173074 biological activity enzyme complexes (e.g. FumA, SdhA, FrdA and CysJ) were invariably decreased in abundance in iron-starved Y. pestis cells. Most of these quantitative decreases appear to be unrelated to population density differences, because they were not observed in cells cultured to stationary vs. exponential phase in iron-replete PMH2 medium(Pieper, R., unpublished data). A decreased pyruvate metabolism rate should be the consequence of the loss of Fe-S cluster enzyme activities in the TCA cycle and may be followed by reduced production of ATP and NADPH reducing equivalents in the electron transport chain. Furthermore, a decreased turnover of citrate may lead to its accumulation in the cytoplasm, which could chelate iron and exacerbate iron starvation [30]. A highly interesting observation was the dramatic abundance and activity increase of PoxB in iron-starved Y. pestis cells, both at 26 and 37 . PoxB activity increases PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/27385778 were independent of Y. pestis cell densities during growth in chemically defined media. poxB expression was reported to be moderately enhanced in Y. pestis cells grown in human plasma vs. LB media [33]. We suggest that the metabolism of pyruvate via the PoxB route compensates for reduced activities of Fe-S cluster enzymes in the TCA cycle. The pathway catalyzed by PoxB is iron-independent. The E. coli ortholog, a thiamin/ flavin-dependent enzyme activated by binding to IM phospholipids, was shown to feed electrons directly from the cytosol to the respiratory chain [52]. To our knowledge, this is the first report linking enhanced PoxB activities in bacteria specifically to iron starvation. PoxB is a potential drug target in the context of intracellular pathogens surviving in environments where iron is sequestered.Additional file 1: Yersinia pestis growth curves in PMH2 medium. Growth curves (OD600) are displayed in graphical form for Y. pestis KIM6+ cell cultures in iron rich and iron-depleted media, at 26 and at 37 . Click here for file [ http://www.biomedcentral.com/content/supplementary/1471-2180-1030-S1.DOC ] Additional file 2: Comprehensive list of differentially displayed Yersinia pestis proteins comparing iron-replete and iron starvation conditions. A variety of qualitative and quantitative data are provided for differentially displayed proteins derived from + Fe vs. -Fe growth conditions, from cell cultures at 26 and at 37 . Click here for file [ http://www.biomedcentral.com/content/supplementary/1471-2180-1030-S2.XLS ] Additional file 3: Comprehensive list of MS and MS2 data for Y. pestis KIM6+ proteins. For all proteins listed in the Tables 1, 2 and 3 and in the Additional File 2, MS and MS2 data were parsed from MALDITOFTOF and LC-nESI-LC-MS/MS datasets. Click here for file [ http://www.biomedcentral.com/content/supplementary/1471-2180-1030-S3.XLS ]Abbreviations 2D: 2-dimensional gel electrophoresis; CBB: Coomassie Brilliant Blue G250; Fe-S: iron-sulfur; IM: inner membrane; usb-MBR: urea/thiou.
