The three domains of the mitochondrial outer membrane protein Mim1 have discrete functions in assembly of the TOM complex.
The assembly of mitochondrial outer membrane proteins is an essential process, mediated by the SAM complex and a set of additional protein modules. We show that one of these, Mim1, is anchored in the outer membrane with its N-terminus exposed to the cytosol and its C-terminus in the mitochondrial intermembrane space. Using an in vitro assay to measure the multi-step pathway for assembly of Tom40 into the TOM complex, we find that an "early reaction" mediated by the SAM complex is regulated by the N-terminal domain of Mim1. In addition, a "late reaction" catalysed by the Sam37 subunit of the SAM complex is also influenced by Mim1. Thus, Mim1 participates at multiple stages in the assembly of the TOM complex.
Department of Biochemistry and Molecular Biology, Monash University, Clayton 3800, Australia.
Franziska
F
Lueder
Trevor
T
Lithgow
D000483:Alleles; D004591:Electrophoresis, Polyacrylamide Gel; D007425:Intracellular Membranes / Q000737:chemistry* / Q000502:physiology; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D026901:Membrane Transport Proteins / Q000737:chemistry / Q000502:physiology*; D033681:Mitochondrial Membrane Transport Proteins; D008962:Models, Theoretical; D012441:Saccharomyces cerevisiae / Q000737:chemistry; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*
C492709:MIM1 protein, S cerevisiae; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D033681:Mitochondrial Membrane Transport Proteins; D029701:Saccharomyces cerevisiae Proteins; C066555:Tom40 protein, S cerevisiae