Assembly of Tim9 and Tim10 into a functional chaperone.
The TIM10 complex is localized in the mitochondrial intermembrane space and mediates insertion of hydrophobic proteins at the inner membrane. We have characterized TIM10 assembly and analyzed the structural properties of its subunits, Tim9 and Tim10. Both proteins are alpha-helical with a protease-resistant central domain, and each self-associates to form mainly dimers and trimers in solution. Tim9 and Tim10 bound to one another with submicromolar affinity in equimolar amounts and assembled in a stable, significantly extended complex that was indistinguishable from the native mitochondrial TIM10 complex. Importantly, the reconstituted TIM10 complex is functional because it bound to the physiological substrate ADP/ATP carrier and displayed chaperone activity in refolding the model substrate firefly luciferase. These data demonstrate that the individual subunits can exist as independent, dynamically self-associating proteins. Assembly into the thermodynamically stable hexameric complex is necessary for the TIM10 chaperone function.
School of Biological Sciences and The Wellcome Trust Centre for Cell Matrix Research, University of Manchester, Manchester M13 9PT, United Kingdom.
Sarah
S
Vial
Hui
H
Lu
Scott
S
Allen
Peter
P
Savory
David
D
Thornton
John
J
Sheehan
Kostas
K
Tokatlidis
D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D002151:Calorimetry; D002942:Circular Dichroism; D003432:Cross-Linking Reagents / Q000494:pharmacology; D004926:Escherichia coli / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D007700:Kinetics; D008027:Light; D008156:Luciferases / Q000378:metabolism; D008565:Membrane Proteins; D026901:Membrane Transport Proteins / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism; D033681:Mitochondrial Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D024101:Mitochondrial Proteins / Q000378:metabolism*; D018832:Molecular Chaperones / Q000378:metabolism*; D011485:Protein Binding; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D012542:Scattering, Radiation; D013997:Time Factors; D014461:Ultracentrifugation
D003432:Cross-Linking Reagents; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D033681:Mitochondrial Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D024101:Mitochondrial Proteins; D018832:Molecular Chaperones; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; C107250:TIM10 protein, S cerevisiae; C116366:Tim9 protein, S cerevisiae; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D008156:Luciferases; D005982:Glutathione Transferase