Staphylococcus aureus sqr Encodes a Type II Sulfide:Quinone Oxidoreductase and Impacts Reactive Sulfur Speciation in Cells.
Recent studies implicate hydrogen sulfide (H2S) oxidation as an important aspect of bacterial antibiotic resistance and sulfide homeostasis. The cst operon of the major human pathogen Staphylococcus aureus is induced by exogenous H2S stress and encodes enzymes involved in sulfide oxidation, including a group I flavoprotein disulfide oxidoreductase sulfide:quinone oxidoreductase (SQR). In this work, we show that S. aureus SQR catalyzes the two-electron oxidation of sodium sulfide (Na2S) into sulfane sulfur (S0) when provided flavin adenine dinucleotide and a water-soluble quinone acceptor. Cyanide, sulfite, and coenzyme A (CoA) are all capable of functioning as the S0acceptor in vitro. This activity requires a C167-C344 disulfide bond in the resting enzyme, with the intermediacy of a C344 persulfide in the catalytic cycle, verified by mass spectrometry of sulfide-reacted SQR. Incubation of purified SQR and S. aureus CstB, a known FeIIpersulfide dioxygenase-sulfurtransferase also encoded by the cst operon, yields thiosulfate from sulfide, in a CoA-dependent manner, thus confirming the intermediacy of CoASSH as a product and substrate of SQR and CstB, respectively. Sulfur metabolite profiling of wild-type, Δsqr, and Δsqr::pSQR strains reveals a marked and specific elevation in endogenous levels of CoASSH and inorganic tetrasulfide in the Δsqr strain. We conclude that SQR impacts the cellular speciation of these reactive sulfur species but implicates other mechanisms not dependent on SQR in the formation of low-molecular weight thiol persulfides and inorganic polysulfides during misregulation of sulfide homeostasis.
Department of Chemistry, Indiana University , Bloomington, Indiana 47405, United States.|Biochemistry Graduate Program, Indiana University , Bloomington, Indiana 47405, United States.
Jiangchuan
J
Shen
Department of Chemistry, Indiana University , Bloomington, Indiana 47405, United States.|Biochemistry Graduate Program, Indiana University , Bloomington, Indiana 47405, United States.
Hui
H
Peng
Department of Chemistry, Indiana University , Bloomington, Indiana 47405, United States.|Laboratory for Biological Mass Spectrometry, Indiana University , Bloomington, Indiana 47405, United States.
Yixiang
Y
Zhang
Department of Chemistry, Indiana University , Bloomington, Indiana 47405, United States.|Laboratory for Biological Mass Spectrometry, Indiana University , Bloomington, Indiana 47405, United States.
Jonathan C
JC
Trinidad
Department of Chemistry, Indiana University , Bloomington, Indiana 47405, United States.|Department of Molecular and Cellular Biochemistry, Indiana University , Bloomington, Indiana 47405, United States.
David P
DP
Giedroc
D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016227:Benzoquinones / Q000737:chemistry / Q000378:metabolism; D055162:Biocatalysis; D004220:Disulfides / Q000737:chemistry / Q000378:metabolism; D005182:Flavin-Adenine Dinucleotide / Q000737:chemistry / Q000378:metabolism; D007700:Kinetics; D008956:Models, Chemical; D008958:Models, Molecular; D015394:Molecular Structure; D009154:Mutation; D000072417:Protein Domains; D055503:Protein Multimerization; D017433:Protein Structure, Secondary; D011808:Quinone Reductases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013211:Staphylococcus aureus / Q000201:enzymology*; D013379:Substrate Specificity; D013440:Sulfides / Q000737:chemistry / Q000378:metabolism; D013447:Sulfites / Q000737:chemistry / Q000378:metabolism; D013455:Sulfur / Q000378:metabolism*
D001426:Bacterial Proteins; D016227:Benzoquinones; D004220:Disulfides; D013440:Sulfides; D013447:Sulfites; D005182:Flavin-Adenine Dinucleotide; C004532:quinone; D013455:Sulfur; D011808:Quinone Reductases; C073412:sulfide quinone reductase; C033479:sodium sulfide