Cardiolipin defines the interactome of the major ADP/ATP carrier protein of the mitochondrial inner membrane

Abstract

Defined mutations in the mitochondrial ADP/ATP carrier (AAC) are associated with certain types of progressive external ophthalmoplegia. AAC is required for oxidative phosphorylation (OXPHOS), and dysregulation of AAC has been implicated in apoptosis. Little is known about the AAC interactome, aside from a known requirement for the phospholipid cardiolipin (CL) and that it is thought to function as a homodimer. Using a newly developed dual affinity tag, we demonstrate that yeast AAC2 physically participates in several protein complexes of distinct size and composition. The respiratory supercomplex and several smaller AAC2-containing complexes, including other members of the mitochondrial carrier family, are identified here. In the absence of CL, most of the defined interactions are destabilized or undetectable. The absence of CL and/or AAC2 results in distinct yet additive alterations in respiratory supercomplex structure and respiratory function. Thus, a single lipid can significantly alter the functional interactome of an individual protein.

Cold-Activated Lipid Dynamics in Adipose Tissue Highlights a Role for Cardiolipin in Thermogenic Metabolism

“…In eukaryotes, cardiolipin is synthesized from phosphatidylglycerol and CDPDAG exclusively in the mitochondria, where it constitutes up to 20% of total mitochondrial membrane lipid (Hostetler and van den Bosch, 1972). With four acyl chains and two negatively charged phosphate groups, cardiolipin has been called the “signature phospholipid” of the inner mitochondrial membrane and binds to a long list of membrane proteins, including respiratory complexes and the ADP-ATP carrier (Beyer and Klingenberg, 1985; Claypool et al, 2008; Eble et al, 1990; Lange et al, 2001; Palsdottir et al, 2003; Shinzawa-Itoh et al, 2007). CRLS1 overexpression in cardiac tissue improves the bioenergetics function of isolated mitochondria, potentially by increasing the ability of mitochondria to deal with increased energetic demands (Kiebish et al, 2012).…”

Dysfunctional cardiac mitochondrial bioenergetic, lipidomic, and signaling in a murine model of Barth syndrome

“…However, mitochondrial function in highly metabolically active tissues such as myocardium is closely integrated with physiologic demands and likely determines the underlying alterations in bioenergetic capacity in vivo in Barth syndrome patients. To identify the upstream mechanism underlying the shift in preference toward glutamate oxidation in the Taz KD mouse, we investigated the adenine nucleotide translocase which exhibits differences in substrate selectivity between various tissues as well as a dependence on cardiolipin for its catalytic activity ( 53,74,79,80 ). The reorganization of cardiolipin and lysocardiolipin molecular species in this Barth syndrome mouse model likely precipitates a dramatic shift in glutamate preference driving ADP/ATP exchange in the mitochondria, thus linking cardiolipin to the substrate-specifi c regulation of respiration.…”

“…4B ). Surprisingly, to modulate ADP/ATP exchange in a substrate-specifi c manner to direct bioenergetic metabolite oxidation ( 52,53 ). To investigate the differences between state 3 substrate utilization in myocardium from the murine model of Barth syndrome, we measured functional ANT activity driven by pyruvate, glutamate, palmitoyl-L -carnitine, and succinate .…”

The ADP/ATP Carrier and Its Relationship to Oxidative Phosphorylation in Ancestral Protist Trypanosoma brucei

“…These detergents are mild, nonionic surfactants that are capable of releasing membrane embedded protein complexes without disrupting internal protein-protein interactions. Furthermore, these surfactants are commonly applied in 2-D PAGE analyses and were extensively used to determine the AAC interactome in mammalian and yeast cells (9,(47)(48)(49). Therefore, detergentsolubilized mt complexes were resolved in a two-step process: by high-resolution clear native (hrCN) PAGE in the first dimension, followed by a second dimension of denaturing Tricine-SDS-PAGE.…”