bims-resufa Biomed News
on Respiratory supercomplex factors
Issue of 2019‒11‒24
two papers selected by
Vera Strogolova
Strong Microbials, Inc

  1. Biochim Biophys Acta Bioenerg. 2019 Nov 13. pii: S0005-2728(19)30165-3. [Epub ahead of print] 148116
    Berg J, Liu J, Svahn E, Ferguson-Miller S, Brzezinski P.
      Data from earlier studies showed that minor structural changes at the surface of cytochrome c oxidase, near 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 form 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 O2-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 ~40 Å from the proton gate of cytochrome c oxidase, may alter the proton-pumping stoichiometry of the enzyme.
    Keywords:  Actinobacteria; Electron transfer; Mitochondria; Mycobacterium smegmatis; Proton pumping; Respiratory chain
  2. Trends Biochem Sci. 2019 Nov 19. pii: S0968-0004(19)30227-0. [Epub ahead of print]
    Brzezinski P.
      Mitochondrial energy conversion involves a chain of membrane-bound proteins that are wired to conduct an electron current, which drives transmembrane proton translocation. These enzymes associate to form supercomplexes, but the functional relevance of the higher-order structures is unknown. A recent study by Letts et al. presents structures of a supercomplex, which suggest how the interaction choreography may control overall functionality.