title: Bacillus subtilis ResA is a thiol-disulfide oxidoreductase involved in cytochrome c synthesis.
abstract: Covalent attachment of heme to apocytochromes c in bacteria occurs on the outside of the cytoplasmic membrane and requires two reduced cysteinyls at the heme binding site. A constructed ResA-deficient Bacillus subtilis strain was found to lack c-type cytochromes. Cytochrome c synthesis was restored in the mutant by: (i) in trans expression of resA; (ii) deficiency in BdbD, a thiol-disulfide oxidoreductase that catalyzes formation of an intramolecular disulfide bond in apocytochrome c after transfer of the polypeptide across the cytoplasmic membrane; or (iii) by addition of the reductant dithiothreitol to the growth medium. In vivo studies of ResA showed that it is membrane-associated with its thioredoxin-like domain on the outside of the cytoplasmic membrane. Analysis of a soluble form of the protein revealed two redox reactive cysteine residues with a midpoint potential of about -340 mV at pH 7. We conclude that ResA, probably together with another thiol-disulfide oxidoreductase, CcdA, is required for the reduction of the cysteinyls in the heme binding site of apocytochrome c.
authors.affiliation: Department of Cell and Organism Biology, Lund University, Sölvegatan 35, SE-22362 Lund, Sweden.
authors.forename: Lýğur S
authors.initials: LS
authors.lastname: Erlendsson
authors.forename: Richard M
authors.initials: RM
authors.lastname: Acheson
authors.forename: Lars
authors.initials: L
authors.lastname: Hederstedt
authors.forename: Nick E
authors.initials: NE
authors.lastname: Le Brun
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000737:chemistry; D001412:Bacillus subtilis / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism; D001483:Base Sequence; D001665:Binding Sites; D002462:Cell Membrane / Q000378:metabolism; D002850:Chromatography, Gel; D003545:Cysteine / Q000737:chemistry; D003574:Cytochrome c Group / Q000096:biosynthesis* / Q000737:chemistry / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D004220:Disulfides; D003576:Electron Transport Complex IV / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D006863:Hydrogen-Ion Concentration; D015151:Immunoblotting; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology*; D008954:Models, Biological; D008969:Molecular Sequence Data; D009154:Mutation; D010084:Oxidation-Reduction; D010455:Peptides / Q000737:chemistry; D010641:Phenotype; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D011490:Protein Disulfide Reductase (Glutathione) / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology*; D017434:Protein Structure, Tertiary; D013879:Thioredoxins / Q000378:metabolism
chemical_list: D000596:Amino Acids; D001426:Bacterial Proteins; C068355:CcdA protein, Bacteria; D003574:Cytochrome c Group; D004220:Disulfides; D008565:Membrane Proteins; D010455:Peptides; D013879:Thioredoxins; D004247:DNA; D011490:Protein Disulfide Reductase (Glutathione); D003576:Electron Transport Complex IV; D003545:Cysteine