Import of preproteins into the mitochondrial matrix is driven by the ATP-dependent interaction of mt-Hsp70 with the peripheral inner membrane import protein Tim44 and the preprotein in transit. We show that Mge1p, a co-chaperone of mt-Hsp70, plays a key role in the ATP-dependent import reaction cycle in yeast. Our data suggest a cycle in which the mt-Hsp70-Tim44 complex forms with ATP: Mge1p promotes assembly of the complex in the presence of ATP. Hydrolysis of ATP by mt-Hsp70 occurs in complex with Tim44. Mge1p is then required for the dissociation of the ADP form of mt-Hsp70 from Tim44 after release of inorganic phosphate but before release of ADP. ATP hydrolysis and complex dissociation are accompanied by tight binding of mt-Hsp70 to the preprotein in transit. Subsequently, the release of mt-Hsp70 from the polypeptide chain is triggered by Mge1p which promotes release of ADP from mt-Hsp70. Rebinding of ATP to mt-Hsp70 completes the reaction cycle.
|Evidence ID||Analyze ID||Interactor||Interactor Systematic Name||Interactor||Interactor Systematic Name||Type||Assay||Annotation||Action||Modification||Phenotype||Source||Reference||Note|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Gene Ontology Term||Gene Ontology Term ID||Qualifier||Aspect||Method||Evidence||Source||Assigned On||Reference||Annotation Extension|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Phenotype||Experiment Type||Experiment Type Category||Mutant Information||Strain Background||Chemical||Details||Reference|
|Evidence ID||Analyze ID||Regulator||Regulator Systematic Name||Target||Target Systematic Name||Experiment||Conditions||Strain||Source||Reference|