Association of the Tim14.Tim16 subcomplex with the TIM23 translocase is crucial for function of the mitochondrial protein import motor.
Tim14 and Tim16 are essential components of the import motor of the mitochondrial TIM23 preprotein translocase. Tim14 contains a J domain in the matrix space that is anchored in the inner membrane by a transmembrane segment. Tim16 is a J-related protein with a moderately hydrophobic segment at its N terminus. The J and J-like domains function in the regulation of the ATPase activity of the Hsp70 chaperone of the import motor. We report here on the role of the hydrophobic segments of Tim16 and Tim14 in the TIM23 translocase. Yeast cells lacking the hydrophobic N-terminal segment in either Tim16 or Tim14 are viable but show growth defects and decreased import rates of matrix-targeted preproteins into mitochondria. The interaction of the Tim14.Tim16 complex with the core complex of the TIM23 translocase is destabilized in these cells. In particular, the N-terminal domain of Tim16 is crucial for the interaction of the Tim14.Tim16 complex with the TIM23 preprotein translocase. Deletion of hydrophobic segments in both, Tim16 and Tim14, is lethal. We conclude that import into the matrix space of mitochondria requires association of the co-chaperones Tim16 and Tim14 with the TIM23 preprotein translocase.
Mokranjac
Dejana
D
Institut für Physiologische Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5, 81377 München, Germany.
Berg
Annette
A
Institut für Physiologische Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5, 81377 München, Germany.
Adam
Alexander
A
Institut für Physiologische Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5, 81377 München, Germany.
Neupert
Walter
W
Institut für Physiologische Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5, 81377 München, Germany.
Hell
Kai
K
Institut für Physiologische Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5, 81377 München, Germany. Electronic address: hell@med.uni-muenchen.de.
D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D008564:Membrane Potentials; D026901:Membrane Transport Proteins / Q000502:physiology*; D008928:Mitochondria / Q000378:metabolism*; D033681:Mitochondrial Membrane Transport Proteins / Q000378:metabolism; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D008954:Models, Biological; D010957:Plasmids / Q000378:metabolism; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D011506:Proteins / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000502:physiology*; D013997:Time Factors
D018840:HSP70 Heat-Shock Proteins; D026901:Membrane Transport Proteins; D033681:Mitochondrial Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; C484526:Pam16 protein, S cerevisiae; D011506:Proteins; D029701:Saccharomyces cerevisiae Proteins; C083081:TIM23 protein, S cerevisiae; C478853:Tim14 protein, S cerevisiae