oxidoreductase activity.

METTMTRRDFLKSAGAAGAAGLVWSQTIPGTLGALEKQEIKGSAKFVPSICEMCTSSCTI EARVEGDKGVFIRGNPKDKSRGGKVCARGGSGFNQLYDPQRLVKPIMRVGERGEGKWKEV SWDEAYTFIAKKLDEIKQKHGAHTVAFTARSGWNKTWFHHLAQAYGSPNIFGHESTCPLA YNMAGRDVFGGSMNRDFAKAKYIINMGHNVFEGIVISYVRQYMEAIENGAKVVTLEPRLS VMAQKASEWHAIKPGHDLPFVLGFMHTLIFENLYDKKFVQKYCTGFEELKASIEPCTPEK MALECDIPADTIKRLAREFAKAAPKAIFDFGHRVTFTPQELELRRAMMMVNALVGNIERD GGMYFGKNASFYNQFLGEEDPKAKGLKKPKTPAYPKVEVPRIDRIGEKDGEFFLANKGEG IVSLVPKATLNELPGVPCKIHGWFIVRNNPVMTQTNADTVIKALKSMDLVVCVDIQVSDT AWFADVVLPDTTYLERDEEFTAGGGKNPSFGIGRQKVVEPLGDAKPGWKIAKELSEKMGL GEYFPWKDIEDYRLQQVDGDLDLLAKLKKDGSASFGVPLMLQEKKSVAEFVKKFPGAASK VNEEGLIDFPKKIQLFSPKLEEVSGKGGLGYEPFKYKEEDELYFVQGKTPVRSNSHTGNV PWLNNLMEYDAIWIHPKTASKLGIKNGDAIELYNKFSSQKSKALITEGVREDTLFGYFGF GHVSKDLKRAYGKGVNSNALMPSFTSPNSGMDLHVFGVKVKKA775

	PMID	Title & Author	Abstract	Year
0	1597189	Cloning and nucleotide sequence of the psrA gene of Wolinella succinogenes polysulphide reductase.T Krafft , M Bokranz, O Klimmek, I Schröder, F Fahrenholz, E Kojro, A Kröger	The polysulphide reductase (formerly sulphur reductase) of Wolinella succinogenes is a component of the phosphorylative electron transport system with polysulphide as the terminal acceptor. Using an antiserum raised against the major subunit (PsrA, 85 kDa) of the enzyme, the corresponding gene (psrA) was cloned from a lambda-gene bank. The N-terminal amino acid sequence of PsrA mapped within the psrA gene product, which also contained an apparent signal peptide. Downstream of the psrA gene two more open reading frames (psrB and psrC) were found. The three genes may form a transcriptional unit with the transcription start site in front of psrA. The three genes were present only once on the genome. PsrA is a hydrophilic protein homologous to the largest subunits of six prokaryotic molybdoenzymes. PsrB is predicted to be hydrophilic, to contain ferredoxin-like cysteine clusters and to be homologous to the smaller hydrophilic subunits of four molybdoenzymes. PsrC is predicted to be a hydrophobic protein that could possibly serve as the membrane anchor of the enzyme.	1992
1	30642986	Respiratory Selenite Reductase from Bacillus selenitireducens Strain MLS10.Michael Wells , Jennifer McGarry , Maissa M Gaye , Partha Basu , Ronald S Oremland , John F Stolz	The putative respiratory selenite [Se(IV)] reductase (Srr) from Bacillus selenitireducens MLS10 has been identified through a polyphasic approach involving genomics, proteomics, and enzymology. Nondenaturing gel assays were used to identify Srr in cell fractions, and the active band was shown to contain a single protein of 80 kDa. The protein was identified through liquid chromatography-tandem mass spectrometry (LC-MS/MS) as a homolog of the catalytic subunit of polysulfide reductase (PsrA). It was found to be encoded as part of an operon that contains six genes that we designated srrE, srrA, srrB, srrC, srrD, and srrF SrrA is the catalytic subunit (80 kDa), with a twin-arginine translocation (TAT) leader sequence indicative of a periplasmic protein and one putative 4Fe-4S binding site. SrrB is a small subunit (17 kDa) with four putative 4Fe-4S binding sites, SrrC (43 kDa) is an anchoring subunit, and SrrD (24 kDa) is a chaperon protein. Both SrrE (38 kDa) and SrrF (45 kDa) were annotated as rhodanese domain-containing proteins. Phylogenetic analysis revealed that SrrA belonged to the PsrA/PhsA clade but that it did not define a distinct subgroup, based on the putative homologs that were subsequently identified from other known selenite-respiring bacteria (e.g., Desulfurispirillum indicum and Pyrobaculum aerophilum). The enzyme appeared to be specific for Se(IV), showing no activity with selenate, arsenate, or thiosulfate, with a Km of 145 ± 53 μM, a V max of 23 ± 2.5 μM min-1, and a k cat of 23 ± 2.68 s-1 These results further our understanding of the mechanisms of selenium biotransformation and its biogeochemical cycle.IMPORTANCE Selenium is an essential element for life, with Se(IV) reduction a key step in its biogeochemical cycle. This report identifies for the first time a dissimilatory Se(IV) reductase, Srr, from a known selenite-respiring bacterium, the haloalkalophilic Bacillus selenitireducens strain MLS10. The work extends the versatility of the complex iron-sulfur molybdoenzyme (CISM) superfamily in electron transfer involving chalcogen substrates with different redox potentials. Further, it underscores the importance of biochemical and enzymological approaches in establishing the functionality of these enzymes.	2019
2	32974951	Elemental sulfur reduction by a deep-sea hydrothermal vent Campylobacterium Sulfurimonas sp. NW10.Shasha Wang , Lijing Jiang , Qitao Hu , Xuewen Liu, Suping Yang , Zongze Shao	Sulfurimonas species (class Campylobacteria, phylum Campylobacterota) were globally distributed and especially predominant in deep-sea hydrothermal environments. They were previously identified as chemolithoautotrophic sulfur-oxidizing bacteria (SOB), whereas little is known about their potential in sulfur reduction. In this report, we found that the elemental sulfur reduction is quite common in different species of genus Sulfurimonas. To gain insights into the sulfur reduction mechanism, growth tests, morphology observation, as well as genomic and transcriptomic analyses were performed on a deep-sea hydrothermal vent bacterium Sulfurimonas sp. NW10. Scanning electron micrographs and dialysis tubing tests confirmed that elemental sulfur reduction occurred without direct contact of cells with sulfur particles while direct access strongly promoted bacterial growth. Furthermore, we demonstrated that most species of Sulfurimonas probably employ both periplasmic and cytoplasmic polysulfide reductases, encoded by genes psrA1 B1 CDE and psrA2 B2 , respectively, to accomplish cyclooctasulfur reduction. This is the first report showing two different sulfur reduction pathways coupled to different energy conservations could coexist in one sulfur-reducing microorganism, and demonstrates that most bacteria of Sulfurimonas could employ both periplasmic and cytoplasmic polysulfide reductases to perform cyclooctasulfur reduction. The capability of sulfur reduction coupling with hydrogen oxidation may partially explain the prevalenceof Sulfurimonas in deep-sea hydrothermal vent environments.	2020
3	19542325	Anaerobic respiration of elemental sulfur and thiosulfate by Shewanella oneidensis MR-1 requires psrA, a homolog of the phsA gene of Salmonella enterica serovar typhimurium LT2.Justin L Burns , Thomas J DiChristina	Shewanella oneidensis MR-1, a facultatively anaerobic gammaproteobacterium, respires a variety of anaerobic terminal electron acceptors, including the inorganic sulfur compounds sulfite (SO3(2-)), thiosulfate (S2O3(2-)), tetrathionate (S4O6(2-)), and elemental sulfur (S(0)). The molecular mechanism of anaerobic respiration of inorganic sulfur compounds by S. oneidensis, however, is poorly understood. In the present study, we identified a three-gene cluster in the S. oneidensis genome whose translated products displayed 59 to 73% amino acid similarity to the products of phsABC, a gene cluster required for S(0) and S2O3(2-) respiration by Salmonella enterica serovar Typhimurium LT2. Homologs of phsA (annotated as psrA) were identified in the genomes of Shewanella strains that reduce S(0) and S2O3(2-) yet were missing from the genomes of Shewanella strains unable to reduce these electron acceptors. A new suicide vector was constructed and used to generate a markerless, in-frame deletion of psrA, the gene encoding the putative thiosulfate reductase. The psrA deletion mutant (PSRA1) retained expression of downstream genes psrB and psrC but was unable to respire S(0) or S2O3(2-) as the terminal electron acceptor. Based on these results, we postulate that PsrA functions as the main subunit of the S. oneidensis S2O3(2-) terminal reductase whose end products (sulfide [HS-] or SO3(2-)) participate in an intraspecies sulfur cycle that drives S(0) respiration.	2009

Krafft T , Gross R , Achim Kröger. The Function of Wolinella succinogenes psr Genes in Electron Transport with Polysulphide as the Terminal Electron Acceptor[J]. European Journal of Biochemistry, 1995, 230.