The presequence pathway is involved in protein sorting to the mitochondrial outer membrane
30.04.2014
Wenz LS, Opalinski L, Schuler MH, Ellenrieder L, Ieva R, Böttinger L, Qiu J, van der Laan M, Wiedemann N, Guiard B, Pfanner N, Becker T.
EMBO Rep. 2014;15(6):678-85.
The mitochondrial outer membrane contains two types of integral membrane proteins, which are membrane-inserted via a beta-barrel or alpha-helical transmembrane anchor. Whereas the biogenesis of beta-barrel protein is well understood, no common import pathway alpha-helical outer membrane proteins has been described. We analyzed here the biogenesis of Om45, which is one of the most abundant outer membrane proteins in baker´s yeast Saccharomyces cerevisiae. So far, it was assumed that Om45 was independently of proteinaceous factors inserted into its target membrane . However, we found that the precursor of Om45 is translocated via the translocase of the outer membrane. Surprisingly, the presequence translocase of the inner membrane promotes import of the large soluble domain of Om45 into the intermembrane space. Finally, Om45 is assembled into the outer membrane by the mitochondrial import (MIM) complex. Thus, the biogenesis of Om45 is a complicated process that involves three translocases of the outer and inner mitochondrial membrane.
