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A conserved arginine residue is critical for stabilizing the N2 FeS cluster in mitochondrial complex I.

Published version
Peer-reviewed

Type

Article

Change log

Authors

Hameedi, Mikhail A 
Grba, Daniel N 
Richardson, Katherine H 
Jones, Andrew JY 
Song, Wei 

Abstract

Respiratory complex I (NADH:ubiquinone oxidoreductase), the first enzyme of the electron-transport chain, captures the free energy released by NADH oxidation and ubiquinone reduction to translocate protons across an energy-transducing membrane and drive ATP synthesis during oxidative phosphorylation. The cofactor that transfers the electrons directly to ubiquinone is an iron-sulfur cluster (N2) located in the NDUFS2/NUCM subunit. A nearby arginine residue (R121), which forms part of the second coordination sphere of the N2 cluster, is known to be posttranslationally dimethylated but its functional and structural significance are not known. Here, we show that mutations of this arginine residue (R121M/K) abolish the quinone-reductase activity, concomitant with disappearance of the N2 signature from the electron paramagnetic resonance (EPR) spectrum. Analysis of the cryo-EM structure of NDUFS2-R121M complex I at 3.7 Å resolution identified the absence of the cubane N2 cluster as the cause of the dysfunction, within an otherwise intact enzyme. The mutation further induced localized disorder in nearby elements of the quinone-binding site, consistent with the close connections between the cluster and substrate-binding regions. Our results demonstrate that R121 is required for the formation and/or stability of the N2 cluster and highlight the importance of structural analyses for mechanistic interpretation of biochemical and spectroscopic data on complex I variants.

Description

Keywords

NADH:ubiquinone oxidoreductase, Yarrowia lipolytica, complex I, cryo-electron microscopy, dimethyl-arginine, electron paramagnetic resonance (EPR), iron–sulfur cluster, Electron Transport Complex I, Fungal Proteins, Iron-Sulfur Proteins, Mitochondrial Proteins, Protein Stability, Yarrowia

Journal Title

J Biol Chem

Conference Name

Journal ISSN

0021-9258
1083-351X

Volume Title

296

Publisher

Elsevier BV
Sponsorship
Medical Research Council (MC_U105663141)
MRC (MC_UU_00015/2)
Medical Research Council (MC_UU_00015/7)