Voltage-coupled conformational dynamics of mitochondrial protein-import channel

01.08.2013

van der Laan M, Schrempp SG, Pfanner N.

Nat Struct Mol Biol. 2013;20(8):915-7.

Nat Struct Mol Biol.         online article

Most mitochondrial proteins are initially synthesized as precursor proteins in the cytosol with amino-terminal, cleavable presequences as targeting signals. These presequences are imported via the translocase of the outer membrane (TOM complex) and the presequence translocase of the inner membrane (TIM23 complex) to the mitochondrial matrix, whereas the final localization of the mature proteins depends on further downstream sorting signals. The membrane potential across the inner mitochondrial membrane is required to open the protein-conducting channel of the TIM23 complex. An amino acid sequence within a transmembrane segment of the central pore-forming Tim23 protein is shown to adapt its secondary structure in response to alterations of the membrane potential. This voltage-dependent conformational rearrangement may represent a key step in the regulation of protein import into mitochondria.