Unravelling the Effects of the Mutation m.3571insC/MT-ND1 on Respiratory Complexes Structural Organization.

Luisa Iommarini,Ivana Kurelac,Massimo Zeviani,Anne Lombes,Anna Ghelli,Giulia Leone,Anna Porcelli,Sara Vidoni,Concetta Tropeano,Giuseppe Gasparre

doi:10.3390/ijms19030764

Abstract

Mammalian respiratory complex I (CI) biogenesis requires both nuclear and mitochondria-encoded proteins and is mostly organized in respiratory supercomplexes. Among the CI proteins encoded by the mitochondrial DNA, NADH-ubiquinone oxidoreductase chain 1 (ND1) is a core subunit, evolutionary conserved from bacteria to mammals. Recently, ND1 has been recognized as a pivotal subunit in maintaining the structural and functional interaction among the hydrophilic and hydrophobic CI arms. A critical role of human ND1 both in CI biogenesis and in the dynamic organization of supercomplexes has been depicted, although the proof of concept is still missing and the critical amount of ND1 protein necessary for a proper assembly of both CI and supercomplexes is not defined. By exploiting a unique model in which human ND1 is allotopically re-expressed in cells lacking the endogenous protein, we demonstrated that the lack of this protein induces a stall in the multi-step process of CI biogenesis, as well as the alteration of supramolecular organization of respiratory complexes. We also defined a mutation threshold for the m.3571insC truncative mutation in mitochondrially encoded NADH:ubiquinone oxidoreductase core subunit 1 (MT-ND1), below which CI and its supramolecular organization is recovered, strengthening the notion that a certain amount of human ND1 is required for CI and supercomplexes biogenesis.

Highlights

Mitochondrial complex I (CI) is the first energy-transducing multiprotein component of the oxidative phosphorylation (OXPHOS) system
To evaluate the role and the amount of the human NADH-ubiquinone oxidoreductase chain 1 (ND1) protein required for a proper CI biogenesis, a series of osteosarcoma-derived cybrid clones bearing different loads of the frameshift m.3571insC/mitochondrially encoded NADH:ubiquinone oxidoreductase core subunit 1 (MT-ND1) mutation were generated (Table 1)
We exploited a set of cell models to investigate how the frameshift m.3571insC/MT-ND1 mutation modulated the abundance of human ND1 subunit and, impacts on the biogenesis and stability of isolated CI and its combination with CIII and CIV in supramolecular entities

Summary

Introduction

Mitochondrial complex I (CI) (reduced nicotinamide adenine dinucleotide NADH: ubiquinone oxidoreductase, EC.1.6.5.3) is the first energy-transducing multiprotein component of the oxidative phosphorylation (OXPHOS) system. Together with ND4L and ND6, it is part of the ubiquinone binding site and is likely to couple the electron transfer with the conformational changes in the membrane domain needed to drive proton translocation across the membrane [5,6,7,8]. These data strongly support the idea that ND1 has a crucial role in maintaining the structural and functional interaction among CI modules

Methods

Results

Conclusion