A conserved glutamic acid in helix VI of cytochrome bo3 influences a key step in oxygen reduction

Nicholas J. Watmough, Andromachi Katsonouri, Richard H. Little, Jeffrey P. Osborne, Elizabeth Furlong-Nickels, Robert B. Gennis, Thomas Brittain, Colin Greenwood

Research output: Contribution to journalArticlepeer-review


We have compared the reactions with dioxygen of wild-type cytochrome bo3 and a mutant in which a conserved glutamic acid at position-286 of subunit I has been changed to an alanine. Flow-flash experiments reveal that oxygen binding and the rate of heme-heme electron transfer are unaffected by the mutation. Reaction of the fully (3-electron) reduced mutant cytochrome bo3 with dioxygen yields a binuclear center which is substantially in the P (peroxy) state, not the well-characterized F (oxyferryl) state which is the product of the reaction of the fully reduced wild-type enzyme with dioxygen [Puustinen, A., et al. (1996) Proc. Natl. Acad. Sci. U.S.A. 93, 1545-1548]. These results confirm that proton uptake is important in controlling the later stages of dioxygen reduction in heme-copper oxidases and show that E286 is an important component of the channel that delivers these protons to the active site.

Original languageEnglish (US)
Pages (from-to)13736-13742
Number of pages7
Issue number44
StatePublished - Nov 4 1997

ASJC Scopus subject areas

  • Biochemistry


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