Description
TIM29 is a subunit of the human mitochondrial carrier translocase, required for protein transport
Sylvie Callegari1, Frank Richter1, Katarzyna Chojnacka2, Daniel C. Jans3,4, Isotta Lorenzi1,
David Pacheu-Grau1, Stefan Jakobs3,4, Christof Lenz5,6, Henning Urlaub5,6, Jan Dudek1,
Agnieszka Chacinska2 and Peter Rehling1,7
1Department of Cellular Biochemistry, University Medical Center Gottingen, Germany
2International Institute of Molecular and Cell Biology, Warsaw, Poland
3Department of NanoBiophotonics, Mitochondrial Structure and Dynamics Group, Max Planck Institute for Biophysical Chemistry,
Gottingen, Germany
4Department of Neurology, University Medical Center Gottingen, Germany
5Bioanalytical Mass Spectrometry Group, Max Planck Institute for Biophysical Chemistry, Gottingen, Germany
6Bioanalytics, Institute for Clinical Chemistry, University Medical Center Gottingen, Germany
7MaxPlanck Institute for Biophysical Chemistry, Gottingen, Germany
The mitochondrial carrier translocase (the TIM22 complex) mediates the insertion of multispanning proteins with internal targeting signals, such as the metabolite carriers, into the inner mitochondrial membrane. The architecture of the TIM22 complex in yeast has been well defined and although the pore-forming unit of this complex, the TIM22 protein, is conserved in higher eukaryotes, additional constituents of the yeast translocase lack human homologs. In fact, very little is known about the mammalian TIM22 complex. We purified the human carrier translocase and, using a proteomics approach, identified a 29 kDa mitochondrial inner membrane protein, TIM29, as a novel, metazoan-specific component of the TIM22 complex. TIM29 is a stoichiometric component of the 440 kDa TIM22 complex and its integration into the complex depends upon the oxidized state of TIM22. Depletion of TIM29 disrupts complex stability and affects the translocation of carrier substrates, resulting in significantly compromised cell growth. The discovery of TIM29 suggests there may be additional metazoan-specific TIM22 associates. Their identification would provide an important insight into the workings of the mammalian TIM22 complex.