Reduction of DsrC trisulfide, thereby linking cytoplasmic reduction of sulfite to energy conservation at membrane; reverse function in sulfur oxidation.
MSTVYALLFIVATLVMLIGLVRKIVQYAKTPAPLKIPTTPAPVTQTGVVLRMFREVVFFE
SLFKSTKWTWIFSWMFHMGLFAVLARHLRYFMDPVPLPIQLLQPIGKYAAFAMVAGLVGL
LVRRIFVDRVRYISAPSDYLWLLMLMVIGLSGLMMTFVVHTDVVMVKQFFDGLFTFSGGA
LPMDFALLVHLLLVAVLMLLLPFSKLLHIPGVFFSPSRNQVDNPREKRHLAPWAKKLEES243
| PMID | Title & Author | Abstract | Year | |
| 0 | 22092713 | Quantitative proteomics of Chlorobaculum tepidum: insights into the sulfur metabolism of a phototrophic green sulfur bacterium.Lasse G Falkenby , Monika Szymanska, Carina Holkenbrink, Kirsten S Habicht, Jens S Andersen, Mette Miller, Niels-Ulrik Frigaard | Chlorobaculum (Cba.) tepidum is a green sulfur bacterium that oxidizes sulfide, elemental sulfur, and thiosulfate for photosynthetic growth. To gain insight into the sulfur metabolism, the proteome of Cba. tepidum cells sampled under different growth conditions has been quantified using a rapid gel-free, filter-aided sample preparation (FASP) protocol with an in-solution isotopic labeling strategy. Among the 2245 proteins predicted from the Cba. tepidum genome, approximately 970 proteins were detected in unlabeled samples, whereas approximately 630-640 proteins were detected in labeled samples comparing two different growth conditions. Wild-type cells growing on thiosulfate had an increased abundance of periplasmic cytochrome c-555 and proteins of the periplasmic thiosulfate-oxidizing SOX enzyme system when compared with cells growing on sulfide. A dsrM mutant of Cba. tepidum, which lacks the dissimilatory sulfite reductase DsrM protein and therefore is unable to oxidize sulfur globules to sulfite, was also investigated. When compared with wild type, the dsrM cells exhibited an increased abundance of DSR enzymes involved in the initial steps of sulfur globule oxidation (DsrABCL) and a decreased abundance of enzymes putatively involved in sulfite oxidation (Sat-AprAB-QmoABC). The results show that Cba. tepidum regulates the cellular levels of enzymes involved in sulfur metabolism and other electron-transferring processes in response to the availability of reduced sulfur compounds. | 2011 |
| 1 | 21233162 | Sulfur globule oxidation in green sulfur bacteria is dependent on the dissimilatory sulfite reductase system.Carina Holkenbrink, Santiago Ocón Barbas , Anders Mellerup , Hiroyo Otaki , Niels-Ulrik Frigaard | Green sulfur bacteria (GSB) oxidize sulfide and thiosulfate to sulfate, with extracellular globules of elemental sulfur as an intermediate. Here we investigated which genes are involved in the formation and consumption of these sulfur globules in the green sulfur bacterium Chlorobaculum tepidum. We show that sulfur globule oxidation is strictly dependent on the dissimilatory sulfite reductase (DSR) system. Deletion of dsrM/CT2244 or dsrT/CT2245, or the two dsrCABL clusters (CT0851-CT0854, CT2247-2250), abolished sulfur globule oxidation and prevented formation of sulfate from sulfide, whereas deletion of dsrU/CT2246 had no effect. The DSR system also seems to be involved in the formation of thiosulfate, because thiosulfate was released from wild-type cells during sulfide oxidation, but not from the dsr mutants. The dsr mutants incapable of complete substrate oxidation oxidized sulfide and thiosulfate about twice as fast as the wild-type, while having only slightly lower growth rates (70-80 % of wild-type). The increased oxidation rates seem to compensate for the incomplete substrate oxidation to satisfy the requirement for reducing equivalents during growth. A mutant in which two sulfide : quinone oxidoreductases (sqrD/CT0117 and sqrF/CT1087) were deleted exhibited a decreased sulfide oxidation rate (~50 % of wild-type), yet formation and consumption of sulfur globules were not affected. The observation that mutants lacking the DSR system maintain efficient growth suggests that the DSR system is dispensable in environments with sufficiently high sulfide concentrations. Thus, the DSR system in GSB may have been acquired by horizontal gene transfer as a response to a need for enhanced substrate utilization in sulfide-limiting habitats. | 2011 |
Grein, F., Pereira, I.A., and Dahl, C. (2010) Biochemical characterization of individual components of the Allochromatium vinosum DsrMKJOP transmembrane complex aids understanding of complex function in vivo. J Bacteriol 192: 6369–6377.