Mechanism of substrate specificity in Bacillus subtilis ResA, a thioredoxin-like protein involved in cytochrome c maturation

Christopher L. Colbert, Qiong Wu, Paul J A Erbel, Kevin H. Gardner, Johann Deisenhofer

Research output: Contribution to journalArticlepeer-review

31 Scopus citations

Abstract

The covalent attachment of heme cofactors to the apo-polypeptides via thioether bonds is unique to the maturation of c-type cytochromes. A number of thiol-disulfide oxidoreductases prepare the apocytochrome for heme insertion in system I and II cytochrome c maturation. Although most thiol-disulfide oxidoreductases are nonspecific, the less common, specific thiol-disulfide oxidoreductases may be key to directing the usage of electrons. Here we demonstrate that unlike other thiol-disulfide oxidoreductases, the protein responsible for reducing oxidized apocytochrome c in Bacillus subtilis, ResA, is specific for cytochrome c550 and utilizes alternate conformations to recognize redox partners. We report solution NMR evidence that ResA undergoes a redox-dependent conformational change between oxidation states, as well as data showing that ResA utilizes a surface cavity present only in the reduced state to recognize a peptide derived from cytochrome c550. Finally, we confirm that ResA is a specific thiol-disulfide oxidoreductase by comparing its reactivity to our mimetic peptide with its reactivity to oxidized glutathione, a nonspecific substrate. This study biochemically demonstrates the specificity of this thioldisulfide oxidoreductase and enables us to outline a structural mechanism of regulating the usage of electrons in a thiol-disulfide oxidoreductase system.

Original languageEnglish (US)
Pages (from-to)4410-4415
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume103
Issue number12
DOIs
StatePublished - Mar 21 2006

Keywords

  • NMR
  • Thiol-disulfide oxidoreductase
  • X-ray crystallography

ASJC Scopus subject areas

  • General

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