The mitochondrial outer membrane contains proteinaceous machineries for the translocation of precursor proteins. The sorting and assembly machinery (SAM) is required for the insertion of ?-barrel proteins into the outer membrane. Sam50 is the channel-forming core subunit of the SAM complex and belongs to the BamA/Sam50/Toc75 family of proteins that have been conserved from Gram-negative bacteria to mitochondria and chloroplasts. These proteins contain one or more N-terminal polypeptide transport-associated (POTRA) domains. POTRA domains can bind precursor proteins, however, different views exist on the role of POTRA domains in the biogenesis of ?-barrel proteins. It has been suggested that the single POTRA domain of mitochondrial Sam50 plays a receptor-like function at the SAM complex. We established a system to monitor the interaction of chemical amounts of ?-barrel precursor proteins with the SAM complex of wild-type and mutant yeast in organello. We report that the SAM complex lacking the POTRA domain of Sam50 efficiently binds ?-barrel precursors, but is impaired in the release of the precursors. These results indicate the POTRA domain of Sam50 is not essential for recognition of ?-barrel precursors but functions in a subsequent step to promote the release of precursor proteins from the SAM complex.
|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|