title: A sulfide:quinone oxidoreductase from Chlorobaculum tepidum displays unusual kinetic properties.
abstract: Sulfide:quinone oxidoreductase (SQR) is the primary sulfide-oxidizing enzyme found in all three domains of life. Of the six phylogenetically distinct types of SQR, four have representatives that have been biochemically characterized. The genome of Chlorobaculum tepidum encodes three SQR homologs. One of these, encoded by CT1087, is a type VI SQR that has been previously shown to be required for growth at high sulfide concentrations and to be expressed in sulfide-dependent manner. Therefore, CT1087 was hypothesized to be a high sulfide adapted SQR. CT1087 was expressed in Escherichia coli with an N-terminal His-tag (CT1087NHis6) and purified by Ni-NTA chromatography. CT1087NHis6 was active and contained FAD as a strongly bound cofactor. The measured kinetic parameters for CT1087NHis6 indicate a low affinity for sulfide and a high enzymatic turnover rate consistent with the hypothesis for its function inferred from genetic and expression data. These are the first kinetic data for a type VI SQR and have implications for structure-function analyses of all SQR's.
authors.affiliation: Department of Biological Sciences, University of Delaware, Newark, DE 19711, USA Delaware Biotechnology Institute, University of Delaware, Newark, DE 19711, USA.
authors.forename: Kevin E
authors.initials: KE
authors.lastname: Shuman
authors.affiliation: Department of Biological Sciences, University of Delaware, Newark, DE 19711, USA Delaware Biotechnology Institute, University of Delaware, Newark, DE 19711, USA School of Marine Science and Policy, University of Delaware, Newark, DE 19711, USA tehanson@udel.edu.
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Hanson
mesh_terms: D019414:Chlorobi / Q000201:enzymology* / Q000254:growth & development / Q000378:metabolism; D004734:Energy Metabolism; D004926:Escherichia coli / Q000235:genetics; D005182:Flavin-Adenine Dinucleotide / Q000378:metabolism; D007700:Kinetics; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D010802:Phylogeny; D013440:Sulfides / Q000378:metabolism*
chemical_list: D013440:Sulfides; D005182:Flavin-Adenine Dinucleotide; D016660:NAD(P)H Dehydrogenase (Quinone)
keywords: Chlorobaculum tepidum; Sulfur2016; energy metabolism; sulfide:quinone oxidoreductase; sulfur metabolism