EPR studies of wild-type and several mutants of cytochrome c oxidase from Rhodobacter sphaeroides: Glu286 is not a bridging ligand in the cytochrome a3-CuB center

David M. Mitchell, Roland Aasa, Pia Ädelroth, Peter Brzezinski, Robert B. Gennis, Bo G. Malmström

Research output: Contribution to journalArticlepeer-review

Abstract

Wild-type and several mutants of cytochrome c oxidase from Rhodobacter sphaeroides were characterized by EPR spectroscopy. A pH-induced g12 signal, seen previously in mammalian cytochrome oxidase and assigned to the presence of a bridging carboxyl ligand in the bimetallic cytochrome a3-CuB site, is found also in the bacterial enzyme. Mutation of glutamate-286 to glutamine inactivates the enzyme but does not affect this signal, demonstrating that the carboxyl group of this residue is not the bridging ligand. Three mutants, M106Q, located one helix turn below a histidine ligand to cytochrome a, and T352A as well as F391Q, located close to the bimetallic center, are shown to affect dramatically the low-spin heme signal of cytochrome a. These mutants are essentially inactive, suggesting that these three mutations result in alterations to cytochrome a that render the oxidase non-functional.

Original languageEnglish (US)
Pages (from-to)371-374
Number of pages4
JournalFEBS Letters
Volume374
Issue number3
DOIs
StatePublished - Nov 6 1995

Keywords

  • Bimetallic cytochrome a-Cu
  • Cytochrome a
  • Cytochrome oxidase
  • EPR spectroscopy
  • Rhodobacter sphaeroides

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology
  • Genetics
  • Cell Biology

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