The role of cardiolipin in the structural organization of mitochondrial membranes

Abstract

Considerable progress has recently been made in understanding the role of cardiolipin in mitochondria. In this brief review, we discuss new data that show how cardiolipin specifically contributes to the lateral organization of mitochondrial membranes. We argue that the function of cardiolipin has to be understood in the context of dynamic membrane assembly rather than static membrane structure, and we propose that remodeling of cardiolipin, i.e. the formation of uniformly substituted molecular species, may reduce the energy barrier of the assembly process.

Fig. 1

Proposed mechanism of transacylation by tafazzin. The enzyme (E) exchanges acyl groups (X, Y, Z) between phospholipid species with the head groups A and B. Two substrates, a phospholipid and a lysophospholipid, bind to the enzyme simultaneously. Acyl exchange between the substrates converts the phospholipid into a lysophospholipid and the lysophospholipid into a phospholipid. Only the phospholipid dissociates and is replaced by another phospholipid to begin another catalytic cycle. The scheme shows how tafazzin catalyzes the transacylation reaction XYA +ZYB → ZYA + XYB.