Sam37 is crucial for formation of the mitochondrial TOM-SAM supercomplex, thereby promoting beta-barrel biogenesis
28.09.2015
Wenz LS, Ellenrieder L, Qiu J, Bohnert M, Zufall N, van der Laan M, Pfanner N, Wiedemann N, Becker T.
J Cell Biol. 2015;210(7):1047-54
The biogenesis of beta-barrel into the outer membrane of mitochondria involves two protein translocases: the translocase of the outer membrane (TOM complex) and the sorting and assembly machinery (SAM complex). TOM and SAM complex form a supercomplex, which promotes efficient beta-barrel biogenesis. The receptor domain of Tom22 is crucial to link both protein complexes. However, the docking site at the SAM complex remained unknown. The SAM core complex consists of the central subunit Sam50 and two peripheral subunits, Sam35 and Sam37. Sam35 recognizes incoming precursor protein. In contrast, the function of Sam37 is poorly understood. We show that Sam37 is crucial for the TOM-SAM supercomplex formation. Sam37 interacts with the cytosolic domain of Tom22. We conclude that Sam37 promotes beta-barrel biogenesis by linking TOM and SAM complexes.
