6HWH

Structure of a functional obligate respiratory supercomplex from Mycobacterium smegmatis

Summary for 6HWH

• Entry DOI: 10.2210/pdb6hwh/pdb
• EMDB information: 0289
• Descriptor: Ubiquinol-cytochrome c reductase iron-sulfur subunit, Cytochrome c oxidase subunit 1, Cytochrome c oxidase polypeptide 4, ... (20 entities in total)
• Functional Keywords: membrane protein, cryo-em, respiratory supercomplex, mycobacterium, electron transport
• Biological source: Mycobacterium smegmatis MC2 155; More
• Total number of polymer chains: 28
• Total formula weight: 710295.51

Authors

Wiseman, B.,Nitharwal, R.G.,Fedotovskaya, O.,Schafer, J.,Guo, H.,Kuang, Q.,Benlekbir, S.,Sjostrand, D.,Adelroth, P.,Rubinstein, J.L.,Brzezinski, P.,Hogbom, M. (deposition date: 2018-10-12, release date: 2018-11-07, Last modification date: 2025-10-01)

Primary citation

Wiseman, B.,Nitharwal, R.G.,Fedotovskaya, O.,Schafer, J.,Guo, H.,Kuang, Q.,Benlekbir, S.,Sjostrand, D.,Adelroth, P.,Rubinstein, J.L.,Brzezinski, P.,Hogbom, M.
Structure of a functional obligate complex III2IV2respiratory supercomplex from Mycobacterium smegmatis.
Nat. Struct. Mol. Biol., 25:1128-1136, 2018

PubMed Abstract: In the mycobacterial electron-transport chain, respiratory complex III passes electrons from menaquinol to complex IV, which in turn reduces oxygen, the terminal acceptor. Electron transfer is coupled to transmembrane proton translocation, thus establishing the electrochemical proton gradient that drives ATP synthesis. We isolated, biochemically characterized, and determined the structure of the obligate IIIIV supercomplex from Mycobacterium smegmatis, a model for Mycobacterium tuberculosis. The supercomplex has quinol:O oxidoreductase activity without exogenous cytochrome c and includes a superoxide dismutase subunit that may detoxify reactive oxygen species produced during respiration. We found menaquinone bound in both the Q and Q sites of complex III. The complex III-intrinsic diheme cytochrome cc subunit, which functionally replaces both cytochrome c and soluble cytochrome c in canonical electron-transport chains, displays two conformations: one in which it provides a direct electronic link to complex IV and another in which it serves as an electrical switch interrupting the connection.

PubMed: 30518849
DOI: 10.1038/s41594-018-0160-3

Experimental method

ELECTRON MICROSCOPY (3.3 Å)