The active-site cysteinyls and hydrophobic cavity residues of resA are important for cytochrome c maturation in Bacillus subtilis

Summary, in English

ResA is an extracytoplasmic membrane-bound thiol-disulfide oxidoreductase required for cytochrome c maturation in Bacillus subtilis. Previous biochemical and structural studies have revealed that the active-site cysteinyls cycle between oxidized and reduced states with a low reduction potential and that, upon reduction, a hydrophobic cavity forms close to the active site. Here we report in vivo studies of ResA-deficient B. subtilis complemented with a series of ResA variants. Using a range of methods to analyze the cellular cytochrome c content, we demonstrated (i) that the N-terminal transmembrane segment of ResA serves principally to anchor the protein to the cytoplasmic membrane but also plays a role in mediating the activity of the protein; (ii) that the active-site cysteines are important for cytochrome c maturation activity; (iii) that Pro141, which forms part of the hydrophobic cavity and which adopts a cis conformation, plays an important role in protein stability; (iv) that Glu80, which lies at the base of the hydrophobic cavity, is important for cytochrome c maturation activity; and, finally, (v) that Pro141 and Glu80 ResA mutant variants promote selective maturation of low levels of one c-type cytochrome, subunit II of the cytochrome c oxidase caa(3), indicating that this apocytochrome is distinct from the other three endogenous c-type cytochromes of B. subtilis.

• Author: Christopher Hodson; Allison Lewin; Lars Hederstedt; Nick Le Brun
• Department/s: Molecular Cell Biology
• Publishing year: 2008
• Language: English
• Pages: 4697-4705
• Publication/Series: Journal of Bacteriology
• Volume: 190
• Issue: 13
• Links: http://dx.doi.org/10.1128/JB.00145-08
• Document type: Journal article
• Publisher: American Society for Microbiology
• Topic: Microbiology
• Status: Published
• ISBN/ISSN/Other: ISSN: 0021-9193