title: Allosteric interactions and proton conducting pathways in proton pumping aa(3) oxidases: heme a as a key coupling element.
abstract: In this paper allosteric interactions in protonmotive heme aa(3) terminal oxidases of the respiratory chain are dealt with. The different lines of evidence supporting the key role of H(+)/e(-) coupling (redox Bohr effect) at the low spin heme a in the proton pump of the bovine oxidase are summarized. Results are presented showing that the I-R54M mutation in P. denitrificans aa(3) oxidase, which decreases by more than 200mV the E(m) of heme a, inhibits proton pumping. Mutational amino acid replacement in proton channels, at the negative (N) side of membrane-inserted prokaryotic aa(3) oxidases, as well as Zn(2+) binding at this site in the bovine oxidase, uncouples proton pumping. This effect appears to result from alteration of the structural/functional device, closer to the positive, opposite (P) surface, which separates pumped protons from those consumed in the reduction of O(2) to 2 H(2)O.
authors.affiliation: Department of Biomedical Science, University of Foggia, Foggia, Italy.
authors.forename: Nazzareno
authors.initials: N
authors.lastname: Capitanio
authors.forename: Luigi Leonardo
authors.initials: LL
authors.lastname: Palese
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Capitanio
authors.forename: Pietro Luca
authors.initials: PL
authors.lastname: Martino
authors.forename: Oliver-Matthias H
authors.initials: OM
authors.lastname: Richter
authors.forename: Bernd
authors.initials: B
authors.lastname: Ludwig
authors.forename: Sergio
authors.initials: S
authors.lastname: Papa
mesh_terms: D000494:Allosteric Regulation; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport / Q000235:genetics; D002417:Cattle; D003576:Electron Transport Complex IV / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006418:Heme / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism; D009154:Mutation; D010231:Paracoccus denitrificans / Q000201:enzymology / Q000235:genetics; D011522:Protons
chemical_list: D001426:Bacterial Proteins; D011522:Protons; C027728:heme a; D006418:Heme; D003576:Electron Transport Complex IV