NADH-Bound AIF Activates the Mitochondrial CHCHD4/MIA40 Chaperone by a Substrate-Mimicry Mechanism

Authors

Chris A Brosey
Runze Shen
John A Tainer

Publication Date

2-1-2025

Journal

EMBO Journal

DOI

10.1038/s44318-024-00360-6

PMID

39806100

PMCID

PMC11832770

PubMedCentral® Posted Date

1-13-2025

PubMedCentral® Full Text Version

Post-print

Abstract

Mitochondrial metabolism requires the chaperoned import of disulfide-stabilized proteins via CHCHD4/MIA40 and its enigmatic interaction with oxidoreductase Apoptosis-inducing factor (AIF). By crystallizing human CHCHD4's AIF-interaction domain with an activated AIF dimer, we uncover how NADH allosterically configures AIF to anchor CHCHD4's β-hairpin and histidine-helix motifs to the inner mitochondrial membrane. The structure further reveals a similarity between the AIF-interaction domain and recognition sequences of CHCHD4 substrates. NMR and X-ray scattering (SAXS) solution measurements, mutational analyses, and biochemistry show that the substrate-mimicking AIF-interaction domain shields CHCHD4's redox-sensitive active site. Disrupting this shield critically activates CHCHD4 substrate affinity and chaperone activity. Regulatory-domain sequestration by NADH-activated AIF directly stimulates chaperone binding and folding, revealing how AIF mediates CHCHD4 mitochondrial import. These results establish AIF as an integral component of the metazoan disulfide relay and point to NADH-activated dimeric AIF as an organizational import center for CHCHD4 and its substrates. Importantly, AIF regulation of CHCHD4 directly links AIF's cellular NAD(H) sensing to CHCHD4 chaperone function, suggesting a mechanism to balance tissue-specific oxidative phosphorylation (OXPHOS) capacity with NADH availability.

Keywords

Humans, Apoptosis Inducing Factor, Mitochondrial Precursor Protein Import Complex Proteins, Mitochondrial Membrane Transport Proteins, NAD, Mitochondria, Mitochondrial Proteins, Protein Binding, Crystallography, X-Ray, Molecular Chaperones, Models, Molecular, Apoptosis-inducing Factor (AIF), CHCHD4/MIA40, OXPHOS, X-ray Crystallography, Small-angle X-ray Scattering (SAXS), Membranes & Trafficking, Organelles, Structural Biology

Published Open-Access

yes

Recommended Citation

Chris A Brosey, Runze Shen, and John A Tainer, "NADH-Bound AIF Activates the Mitochondrial CHCHD4/MIA40 Chaperone by a Substrate-Mimicry Mechanism" (2025). Faculty, Staff and Student Publications. 5040.
https://digitalcommons.library.tmc.edu/uthgsbs_docs/5040