Phosphatidylethanolamine and cardiolipin differentially affect the stability of mitochondrial respiratory chain supercomplexes
10.09.2102
Böttinger L, Horvath SE, Kleinschroth T, Hunte C, Daum G, Pfanner N, Becker T.
J Mol Biol. 2012;423(5):677-86.
Phosphatidylethanolamine (PE) and cardiolipin (CL) are the most abundant non-bilayer forming phospholipids in the eukaryotic cell. CL is synthesized in the mitochondrial inner membrane, whereas PE is synthesized by four different pathways. However, the activity of the mitochondrial inner membrane protein phosphatidylserine decarboxylase 1 is the major source of the cellular PE in yeast. Lack of CL leads to destabilization of several mitochondrial protein complexes, reduced activity of the respiratory chain and consequently to a reduced membrane potential across the mitochondrial inner membrane. Since the membrane potential and the stability of protein translocases are crucial for protein import into the matrix and into the inner membrane the protein uptake into mitochondria lacking CL is impaired. Although PE is the most abundant non-bilayer phospholipid the requirement for protein complex stability and function was not studied yet. We demonstrate that in PE depleted mitochondria protein import is blocked by a reduced membrane potential, which is caused by a decreased activity of the respiratory chain. In contrast to CL PE is not required for the stability of membrane-bound protein complexes. We observed even a stabilization of respiratory chain supercomplexes in mitochondria with reduced PE content. Thus, PE and CL affect the respiratory chain in different ways.
