The respiratory supercomplex from C. glutamicum

Structure. 2022 Mar 3;30(3):338-349.e3. doi: 10.1016/j.str.2021.11.008. Epub 2021 Dec 14.

Abstract

Corynebacterium glutamicum is a preferentially aerobic gram-positive bacterium belonging to the phylum Actinobacteria, which also includes the pathogen Mycobacterium tuberculosis. In these bacteria, respiratory complexes III and IV form a CIII2CIV2 supercomplex that catalyzes oxidation of menaquinol and reduction of dioxygen to water. We isolated the C. glutamicum supercomplex and used cryo-EM to determine its structure at 2.9 Å resolution. The structure shows a central CIII2 dimer flanked by a CIV on two sides. A menaquinone is bound in each of the QN and QP sites in each CIII and an additional menaquinone is positioned ∼14 Å from heme bL. A di-heme cyt. cc subunit electronically connects each CIII with an adjacent CIV, with the Rieske iron-sulfur protein positioned with the iron near heme bL. Multiple subunits interact to form a convoluted sub-structure at the cytoplasmic side of the supercomplex, which defines a path for proton transfer into CIV.

Keywords: Actinobacteria; Bioenergetics; Electron transfer; cytochrome bc(1); cytochrome c oxidase; electrochemical potential; energy conservation; membrane protein; proton transfer; respiration.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Electron Transport
  • Electron Transport Complex IV* / chemistry
  • Heme*
  • Mitochondrial Membranes / metabolism
  • Oxidation-Reduction
  • Vitamin K 2 / metabolism

Substances

  • Vitamin K 2
  • Heme
  • Electron Transport Complex IV

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