ATP-binding cassette (ABC) transporters are a large superfamily of proteins that mediate substrate translocation across biological membranes. We aimed to define the intramolecular interactions that contribute to quaternary assembly of a eukaryotic ABC transporter, and determine how the architecture of this protein influences its biogenesis within the secretory pathway. We used chemical cross-linking approaches to map inter-domain interactions in the yeast ABC transporter, Yor1p, which functions as a pleiotropic drug pump at the plasma membrane. We have defined interactions between the two nucleotide binding domains (NBDs) and between the NBDs and specific intracellular loops (ICLs) that are consistent with current structural models of bacterial ABC exporters. Furthermore, we detected relatively weak NBD-NBD and ICL-ICL interactions that may correspond to transient sites of cross-talk between domains required for coupling of ATP hydrolysis with substrate translocation. Mutation of a key residue in ICL2 caused misassembly of the altered protein, leading to increased sensitivity to the mitochondrial poison, oligomycin. We identified intragenic suppressing mutations that rescued the oligomycin resistance associated with this aberrant protein, and demonstrated that the suppressing mutations restored multiple inter-domain interfaces. Together, our biochemical and genetic approaches contribute to a greater understanding of the architecture of this important class of proteins and provide insight into the quality control surveillance that regulates their biogenesis and deployment within the eukaryotic cell.
|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||Annotation Extension||Reference|
|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||Assay||Construct||Conditions||Strain Background||Reference|