The major biochemical activities ascribed to Kem1p/Xrn1p of Saccharomyces cerevisiae are 5'-3' exoribonuclease functioning in RNA turnover and a microtubule-binding protein. Mutational analysis has shown that Kem1p/Xrn1p participates in microtubule-related functions such as nuclear fusion (karyogamy) during mating, chromosome transmission, and spindle pole body duplication. Here, evidence is presented that Kem1p plays a specific role in nuclear fusion by affecting, at the posttranscriptional level, the pheromone induction of the karyogamy-specific transcription factor Kar4p and the expression of Rok1p, a putative RNA helicase. We found that Rok1p itself also affects the pheromone induction of Kar4p and thereby participates in nuclear fusion. Analysis of the active-site mutations, xrn1-D206A or D208A, shows that nuclear fusion as well as the Rok1p synthesis do not require the exoribonuclease activity of Kem1p. Our data provide an important insight into the gene-specific regulatory function mediated by the general RNA-modulating enzymes.
|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|