The preprotein translocase of the inner mitochondrial membrane: evolutionary conservation of targeting and assembly of Tim17.
The preprotein translocase of the inner mitochondrial membrane has only been described in Saccharomyces cerevisiae to date. We report that the essential subunit Tim17 is highly conserved in evolution. The targeting and assembly of yeast Tim17 as well as that of human and Drosophila melanogaster Tim17 were characterized with isolated yeast mitochondria. Targeting signals in the mature protein direct the Tim17 precursors to the receptor Tom70 on the mitochondrial surface. In a membrane potential-dependent step the precursors insert into the inner membrane, adopt a characteristic topology and assemble with Tim23. The mechanisms of targeting and assembly were indistinguishable between the Tim17s from distinct organisms, indicating a high evolutionary conservation.
Institut für Biochemie und Molekularbiologie, Universität, Freiburg, Germany.
U
U
Bömer
J
J
Rassow
N
N
Zufall
N
N
Pfanner
M
M
Meijer
A C
AC
Maarse
D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics*; D001483:Base Sequence; D001692:Biological Transport; D002352:Carrier Proteins / Q000096:biosynthesis / Q000235:genetics*; D017124:Conserved Sequence; D004331:Drosophila melanogaster; D029968:Escherichia coli Proteins; D006801:Humans; D007425:Intracellular Membranes / Q000201:enzymology; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics*; D026901:Membrane Transport Proteins; D008928:Mitochondria / Q000201:enzymology*; D033681:Mitochondrial Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D008969:Molecular Sequence Data; D011487:Protein Conformation; D051381:Rats; D012097:Repressor Proteins; D000069816:SEC Translocation Channels; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D000081416:SecA Proteins
D001426:Bacterial Proteins; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D033681:Mitochondrial Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D012097:Repressor Proteins; D000069816:SEC Translocation Channels; D029701:Saccharomyces cerevisiae Proteins; C091191:TIM17 protein, S cerevisiae; C083081:TIM23 protein, S cerevisiae; D000251:Adenosine Triphosphatases; D000081416:SecA Proteins