ADP/ATP carrier protein from beef heart mitochondria has high amounts of tightly bound cardiolipin, as revealed by phosphorus-31 nuclear magnetic resonance

Abstract

An unusual binding of cardiolipin to the ADP/ATP carrier has been found, which is distinguished by the relatively large amount and by the tightness of binding. High-resolution 31P NMR studies on the detergent-solubilized ADP/ATP carrier from beef heart mitochondria revealed narrow signals from phosphatidylcholine and phosphatidylethanolamine and a broadened signal of 30-40-Hz line width, suggestive of cardiolipin. Line broadening of this magnitude is to be expected when tumbling of the whole protein-detergent micelle is the only source of phosphorus spin-spin relaxation. Thus a strong immobilization of the protein-bound cardiolipin is inferred. By sucrose density gradient centrifugation phosphatidylcholine and phosphatidylethanolamine were removed, while approximately six +/- one molecules of cardiolipin remained tightly bound in the dimeric protein molecule. The cardiolipin binding was stable against treatment with sodium dodecyl sulfate although release of the inhibitor carboxyatractyloside revealed at least partial protein denaturation. Ca2+ ions did not readily interact either with the bound cardiolipin. Complete detachment of the bound phospholipid was achieved by a short heat pulse in the presence of sodium dodecyl sulfate. Denaturation of the carrier protein by guanidinium chloride or NaClO4 also led to release of the bound phospholipid. Thus different stages of protein denaturation must be envisaged.

NDPK-D (NM23-H4)-mediated externalization of cardiolipin enables elimination of depolarized mitochondria by mitophagy

“…Many IMM proteins have CL-binding domains, thus limiting free exchange and redistribution of the phospholipid to the OMM. [28][29][30][31][32][33][34][35][36] In some of these proteins, CL molecules are buried 'deeply' within multimeric protein complexes (like in electron-transporting respirasomes 35,36 ), whereas in the others the affinity and accessibility of CL for translocations seem to be less restricted (e.g., TIM40 37 ). Although the exact amounts of CL in the two pools -free versus bound -have not been established, it is likely that in normally functioning mitochondria, the majority of the IMM CLs is not readily mobilized.…”

The Cardiolipin Transacylase, Tafazzin, Associates with Two Distinct Respiratory Components Providing Insight into Barth Syndrome

“…Once produced, ATP is transported across the IM by AAC2 in exchange for ADP. Both AAC2 and the ATP synthase are structurally associated with CL (Beyer and Klingenberg, 1985;Eble et al, 1990;Nury et al, 2005) as opposed to simply embedded in membranes that happen to contain CL. Very little is known about how so-called structural phospholipids are incorporated into the final tertiary and/or quaternary structure of membrane proteins.…”

Interaction of peroxidized cardiolipin with rat‐heart mitochondrial membranes: Induction of permeability transition and cytochrome c release

“…The fact that the effect of peroxidized cardiolipin on the MPT induction is modulated by ligands and inhibitors of ADP carrier, points to an involvement of this protein system in this process. Cardiolipins were shown to be tightly associated with ANT with a stoichiometry of 3 cardiolipins per protein monomer [32]. It was suggested that interactions between two monomers of the ANT is mediated by cardiolipins, which could stabilize the dimer and structure, by controlling the conformational changes and participate in triggering a concerted ADP/ATP exchange [33].…”