| 19542325 |
Burns JL, DiChristina TJ: 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. Appl Environ Microbiol. 2009 Aug;75(16):5209-17. Epub 2009 Jun 19.
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. |
12(0,0,2,2) |