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Regulation of the yeast mitochondrial respiratory complex IV activity by the major isoform of the ADP‐ATP carrier
Author(s) -
Ogunbona Oluwaseun Basit,
Baile Matthew G,
Claypool Steven M
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.1007.3
Subject(s) - oxidative phosphorylation , biology , biochemistry , cardiolipin , mitochondrion , yeast , cytochrome c oxidase , microbiology and biotechnology , gene isoform , respiratory chain , point mutation , electron transport chain , mutation , chemistry , gene , phospholipid , membrane
Protein‐protein interactions underlie many biological processes. The ADP/ATP carrier (AAC) forms an evolutionarily‐conserved, cardiolipin‐dependent interaction with the respiratory supercomplexes. Interestingly, in yeast lacking Aac2p the activity of respiratory complex IV ( cytochrome c oxidase or COX) is reduced suggesting that this interaction is of functional significance. The regulation of COX activity and by extension, of oxidative phosphorylation by AACs is not clearly understood. Here, we leveraged a transport‐dead pathogenic AAC2 point mutant discovered in a patient with hypertrophic cardiomyopathy and mild myopathy to determine whether the reduction in complex IV activity in the absence of Aac2p reflects the absence of the interaction between AACs and components of the electron transport chain and/or the absence of nucleotide transport (i.e. Aac2p function). Using a CRISPR‐Cas9 based strategy, we established yeast strains with either an AAC2 frameshift deletion or an AAC2 A137D point mutation in the presence or absence of the minor AAC isoforms, Aac1p and Aac3p. Importantly, the pathogenic A137D allele of AAC2 is expressed normally and still interacts with components of the yeast respiratory supercomplex but is unable to support growth on respiratory media due to its inability to transport ADP/ATP. Interestingly, complex IV activity is significantly reduced in yeast strains lacking Aac2p activity (P<0.05). Moreover, in the absence of Aac2p function, the expression levels of complex IV subunits encoded by the mitochondrial genome are specifically reduced. Thus these new pieces of evidence suggest that Aac2p nucleotide transport function and not the physical interaction with the respiratory supercomplexes is required for full COX activity. Mechanistically, the absence of Aac2 function specifically impairs expression of mitochondria DNA‐encoded COX subunits. Given that oxidative phosphorylation accounts for the majority of cellular ATP production, uncovering this important line of regulation is critical for further understanding of the various role the mitochondria play in healthy and diseased state. Support or Funding Information “THIS WORK WAS SUPPORTED BY AMERICAN HEART ASSOCIATION GRANT #15PRE24480066 (Oluwaseun Ogunbona) and NATIONAL INSTITUTES OF HEALTH GRANT NIH/NHLBI 1R01HL108882 ‐ 01A1 (Steven Claypool)