Structure of the turnover-ready state of an ancestral respiratory complex I.

Ivanov BS., Bridges HR., Jarman OD., Hirst J.

Respiratory complex I is pivotal for cellular energy conversion, harnessing energy from NADH:ubiquinone oxidoreduction to drive protons across energy-transducing membranes for ATP synthesis. Despite detailed structural information on complex I, its mechanism of catalysis remains elusive due to lack of accompanying functional data for comprehensive structure-function analyses. Here, we present the 2.3-Å resolution structure of complex I from the α-proteobacterium Paracoccus denitrificans, a close relative of the mitochondrial progenitor, in phospholipid-bilayer nanodiscs. Three eukaryotic-type supernumerary subunits (NDUFS4, NDUFS6 and NDUFA12) plus a novel L-isoaspartyl-O-methyltransferase are bound to the core complex. Importantly, the enzyme is in a single, homogeneous resting state that matches the closed, turnover-ready (active) state of mammalian complex I. Our structure reveals the elements that stabilise the closed state and completes P. denitrificans complex I as a unified platform for combining structure, function and genetics in mechanistic studies.

DOI

10.1038/s41467-024-53679-3

Type

Journal article

Journal

Nat Commun

Publication Date

29/10/2024

Volume

15

Keywords

Electron Transport Complex I, Paracoccus denitrificans, Models, Molecular, Bacterial Proteins, Protein Subunits, Methyltransferases

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