title: The cysteine desulfhydrase CdsH is conditionally required for sulfur mobilization to the thiamine thiazole in Salmonella enterica.
abstract: Thiamine pyrophosphate is a required coenzyme that contains a mechanistically important sulfur atom. In Salmonella enterica, sulfur is trafficked to both thiamine biosynthesis and 4-thiouridine biosynthesis by the enzyme ThiI using persulfide (R-S-S-H) chemistry. It was previously reported that a thiI mutant strain could grow independent of exogenous thiamine in the presence of cysteine, suggesting there was a second mechanism for sulfur mobilization. Data reported here show that oxidation products of cysteine rescue the growth of a thiI mutant strain by a mechanism that requires the transporter YdjN and the cysteine desulfhydrase CdsH. The data are consistent with a model in which sulfide produced by CdsH reacts with cystine (Cys-S-S-Cys), S-sulfocysteine (Cys-S-SO3 (-)), or another disulfide to form a small-molecule persulfide (R-S-S-H). We suggest that this persulfide replaced ThiI by donating sulfur to the thiamine sulfur carrier protein ThiS. This model describes a potential mechanism used for sulfur trafficking in organisms that lack ThiI but are capable of thiamine biosynthesis.
authors.affiliation: Department of Microbiology, University of Georgia, Athens, Georgia, USA.
authors.forename: Lauren D
authors.initials: LD
authors.lastname: Palmer
authors.affiliation: Department of Microbiology, University of Georgia, Athens, Georgia, USA.
authors.forename: Man Him
authors.initials: MH
authors.lastname: Leung
authors.affiliation: Department of Microbiology, University of Georgia, Athens, Georgia, USA dmdowns@uga.edu.
authors.forename: Diana M
authors.initials: DM
authors.lastname: Downs
mesh_terms: D003542:Cystathionine gamma-Lyase / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D019779:Salmonella enterica / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D013455:Sulfur / Q000378:metabolism*; D013831:Thiamine / Q000096:biosynthesis* / Q000737:chemistry
chemical_list: D013455:Sulfur; D003542:Cystathionine gamma-Lyase; D013831:Thiamine