bims-resufa Biomed News
on Respiratory supercomplex factors
Issue of 2020‒09‒13
two papers selected by
Vera Strogolova
Strong Microbials, Inc

  1. Structure. 2020 Sep 03. pii: S0969-2126(20)30290-2. [Epub ahead of print]
      The Saccharomyces cerevisiae respiratory supercomplex factor 2 (Rcf2) is a 224-residue protein located in the mitochondrial inner membrane where it is involved in the formation of supercomplexes composed of cytochrome bc1 and cytochrome c oxidase. We previously demonstrated that Rcf2 forms a dimer in dodecylphosphocholine micelles, and here we report the solution NMR structure of this Rcf2 dimer. Each Rcf2 monomer has two soluble α helices and five putative transmembrane (TM) α helices, including an unexpectedly charged TM helix at the C terminus, which mediates dimer formation. The NOE contacts indicate the presence of inter-monomer salt bridges and hydrogen bonds at the dimer interface, which stabilize the Rcf2 dimer structure. Moreover, NMR chemical shift change mapping upon lipid titrations as well as molecular dynamics analysis reveal possible structural changes upon embedding Rcf2 into a native lipid environment. Our results contribute to the understanding of respiratory supercomplex formation and regulation.
    Keywords:  Hig protein; charge zipper; membrane protein; mitochondria; molecular dynamics; protein-lipid interactions; solution structure
  2. Biochim Biophys Acta Bioenerg. 2020 Sep 08. pii: S0005-2728(20)30155-9. [Epub ahead of print] 148305
      The inner membrane of mitochondria is known for its low lipid-to-protein ratio. Calculations based on the size and the concentration of the principal membrane components, suggest about half of the hydrophobic volume of the membrane is occupied by proteins. Such high degree of crowding is expected to strain the hydrophobic coupling between proteins and lipids unless stabilizing mechanisms are in place. Both protein supercomplexes and cardiolipin are likely to be critical for the integrity of the inner mitochondrial membrane because they reduce the energy penalty of crowding.
    Keywords:  cardiolipin; lipids; membrane; mitochondria; protein