Bacillus subtilis ResA is a thiol-disulfide oxidoreductase involved in cytochrome c synthesis

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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 thioldisulfide 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.

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  • University of East Anglia
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Microbiology
  • Biochemistry and Molecular Biology
Original languageEnglish
Pages (from-to)17852-17858
JournalJournal of Biological Chemistry
Volume278
Issue number20
Publication statusPublished - 2003
Publication categoryResearch
Peer-reviewedYes