Journal
BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS
Volume 1861, Issue 2, Pages -Publisher
ELSEVIER
DOI: 10.1016/j.bbabio.2019.148116
Keywords
Mycobacterium smegmatis; Proton pumping; Respiratory chain; Electron transfer; Actinobacteria; Mitochondria
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Funding
- Knut and Alice Wallenberg Foundation
- Swedish Research Council
- NIH [R01 GM26916]
- MSU Foundation Strategic Partnership Grant Mitochondrial Science Medicine
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Data from earlier studies showed that minor structural changes at the surface of cytochrome c oxidase, in one of the proton-input pathways (the D pathway), result in dramatically decreased activity and a lower proton-pumping stoichiometry. To further investigate how changes around the D pathway orifice influence functionality of the enzyme, here we modified the nearby C-terminal loop of subunit I of the Rhodobacter sphaeroides cytochrome c oxidase. Removal of 16 residues from this flexible surface loop resulted in a decrease in the proton-pumping stoichiometry to <50% of that of the wild-type enzyme. Replacement of the protonatable residue Glu552, part of the same loop, by an Ala, resulted in a similar decrease in the proton-pumping stoichiometry without loss of the O-2-reduction activity or changes in the proton-uptake kinetics. The data show that minor structural changes at the orifice of the D pathway, at a distance of similar to 40 angstrom from the proton gate of cytochrome c oxidase, may alter the proton-pumping stoichiometry of the enzyme.
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