Mechanism of electron transport during thiosulfate oxidation in an obligately mixotrophic bacterium Thiomonas bhubaneswarensis strain S10 (DSM 18181^T)

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• 作者：Kunwar Digvijay Narayan ; Surendra Chandra Sabat…
• 关键词：Thiosulfate oxidation ; Respiratory electron transport ; Effect of inhibitors ; Uncouplers ; Terminal oxidase ; Whole genome ; Sox pathway
• 刊名：Applied Microbiology and Biotechnology
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：101
• 期：3
• 页码：1239-1252
• 全文大小：
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Microbiology; Microbial Genetics and Genomics; Biotechnology;
• 出版者：Springer Berlin Heidelberg
• ISSN：1432-0614
• 卷排序：101

文摘

This study describes the thiosulfate-supported respiratory electron transport activity of Thiomonas bhubaneswarensis strain S10 (DSM 18181T). Whole-genome sequence analysis revealed the presence of complete sox (sulfur oxidation) gene cluster (soxCDYZAXB) including the sulfur oxygenase reductase (SOR), sulfide quinone reductase (SQR), sulfide dehydrogenase (flavocytochrome c (fcc)), thiosulfate dehydrogenase (Tsd), sulfite dehydrogenase (SorAB), and intracellular sulfur oxidation protein (DsrE/DsrF). In addition, genes encoding respiratory electron transport chain components viz. complex I (NADH dehydrogenase), complex II (succinate dehydrogenase), complex III (ubiquinone-cytochrome c reductase), and various types of terminal oxidases (cytochrome c and quinol oxidase) were identified in the genome. Using site-specific electron donors and inhibitors and by analyzing the cytochrome spectra, we identified the shortest thiosulfate-dependent electron transport chain in T. bhubaneswarensis DSM 18181T. Our results showed that thiosulfate supports the electron transport activity in a bifurcated manner, donating electrons to quinol (bd) and cytochrome c (Caa₃) oxidase; these two sites (quinol oxidase and cytochrome c oxidase) also showed differences in their phosphate esterification potential (oxidative phosphorylation efficiency (P/O)). Further, it was evidenced that the substrate-level phosphorylation is the major contributor to the total energy budget in this bacterium.