RT Journal Article SR Electronic T1 The respiratory supercomplex from C. glutamicum JF bioRxiv FD Cold Spring Harbor Laboratory SP 2021.06.16.448340 DO 10.1101/2021.06.16.448340 A1 Agnes Moe A1 Terezia Kovalova A1 Sylwia Król A1 David J. Yanofsky A1 Michael Bott A1 Dan Sjöstrand A1 John L. Rubinstein A1 Martin Högbom A1 Peter Brzezinski YR 2021 UL http://biorxiv.org/content/early/2021/06/16/2021.06.16.448340.abstract AB Corynebacterium glutamicum is a preferentially aerobic Gram-positive bacterium belonging to the Actinobacteria phylum, which also includes the pathogen Mycobacterium tuberculosis. In the respiratory chain of these bacteria, complexes III (CIII) and IV (CIV) form a CIII2CIV2 supercomplex that catalyzes oxidation of menaquinol and reduction of dioxygen to water. Electron transfer within the CIII2CIV2 supercomplex is linked to transmembrane proton translocation, which maintains an electrochemical proton gradient that drives ATP synthesis and transport processes. 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 each side. One menaquinone is bound in each of the QN and QP sites in each CIII, near the cytoplasmic and periplasmic sides, respectively. In addition, we identified a menaquinone positioned ~14 Å from heme bL on the periplasmic side. A di-heme cyt. cc subunit provides an electronic connection between each CIII monomer and the adjacent CIV. In CIII2, the Rieske iron-sulfur (FeS) proteins are 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 novel path that conducts protons into CIV.Competing Interest StatementThe authors have declared no competing interest.