Three intragenic second-site suppressors, P353L, T237I, and L390F, were identified that suppressed two mutations in, and one adjacent to, the P-loop in the beta-subunit of the yeast F1-ATPase. The crystal structure of bovine F1-ATPase (Abrahams, J. P., Leslie, A. G. W., Lutter, R., and Walker, J. E. (1994) Nature 370, 621-628) shows that these suppressor residues are located in the nucleotide-binding domain. Specific hypotheses have been formulated that suggest the conformational coupling of the P-loop with the suppressor sites. P353L is in a "catch" region, which forms unique interactions with the gamma-subunit in the three different conformational states of the catalytic site. The identification of this suppressor mutation demonstrates genetically that the catch region is conformationally coupled to the P-loop. T237I is shown to interact with Lys-209, which occurs just after the P-loop. This suggests that this interaction changes the conformation of the P-loop to suppress the initial mutation. L390F interacts with Ala-181, which is adjacent to the P-loop. The mechanism of this suppression is suggested to occur through the interactions of L390F with Ala-181. These results identify critical interactions that modulate the structure of the P-loop and thus the biochemistry of the enzyme.
|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|