Ubiquitin and the SCFGrr1 ubiquitin ligase complex are involved in the signalling pathway activated by external amino acids in Saccharomyces cerevisiae

In response to external amino acids, the permease-like sensor Ssy1 of Sacch aromyces cerevisiae activates a pathway leading to transcriptional inductio n of several permease genes including AGP1 and PTR2, we previously reported that AGP1 induction requires Grr1, the F-box protein part of the SCFGrr1 u biquitin-ligase complex. We show here that ubiquitin, other components of S CFGrr1 and the ubiquitin-conjugating enzyme Cdc34 are essential for A GPI a nd PTR2 induction. This suggests that transduction to these genes of the am ino acid signal generated by Ssy1 involves an SCFGrr1-catalysed ubiquitinat ion step. (C) 2001 Published by Elsevier Science B.V. on behalf of the Fede ration of European Biochemical Societies.