The H channel is not a proton transfer path in yeast cytochrome c oxidase

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Malkamäki , A , Meunier , B , Reidelbach , M , Rich , P R & Sharma , V 2019 , ' The H channel is not a proton transfer path in yeast cytochrome c oxidase ' , Biochimica et Biophysica Acta. Bioenergetics , vol. 1860 , no. 9 , pp. 717-723 . https://doi.org/10.1016/j.bbabio.2019.07.012

Title: The H channel is not a proton transfer path in yeast cytochrome c oxidase
Author: Malkamäki, Aapo; Meunier, Brigitte; Reidelbach, Marco; Rich, Peter R.; Sharma, Vivek
Contributor: University of Helsinki, Materials Physics
University of Helsinki, Materials Physics
University of Helsinki, Department of Physics
Date: 2019-09-01
Language: eng
Number of pages: 7
Belongs to series: Biochimica et Biophysica Acta. Bioenergetics
ISSN: 0005-2728
URI: http://hdl.handle.net/10138/304661
Abstract: Cytochrome c oxidases (CcOs) in the respiratory chains of mitochondria and bacteria are primary consumers of molecular oxygen, converting it to water with the concomitant pumping of protons across the membrane to establish a proton electrochemical gradient. Despite a relatively well understood proton pumping mechanism of bacterial CcOs, the role of the H channel in mitochondrial forms of CcO remains debated. Here, we used site-directed mutagenesis to modify a central residue of the lower span of the H channel, Q413, in the genetically tractable yeast Saccharomyces cerevisiae. Exchange of Q413 to several different amino acids showed no effect on rates and efficiencies of respiratory cell growth, and redox potential measurements indicated minimal electrostatic interaction between the 413 locus and the nearest redox active component heme a. These findings clearly exclude a primary role of this section of the H channel in proton pumping in yeast CcO. In agreement with the experimental data, atomistic molecular dynamics simulations and continuum electrostatic calculations on wildtype and mutant yeast CcOs highlight potential bottlenecks in proton transfer through this route. Our data highlight the preference for neutral residues in the 413 locus, precluding sufficient hydration for formation of a proton conducting wire.
Subject: Cell respiration
Electron transfer
FIELD
HEME
MD simulations
MECHANISM
MOLECULAR-DYNAMICS
Mitochondria
PH
Proton pumping
SITE
SUPERFAMILY
1182 Biochemistry, cell and molecular biology
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