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Reports

The CK2 phosphorylation of catalytic domain of Cdc34 modulates its activity at the G₁ to S transition in Saccharomyces cerevisiae

Paola Coccetti, Farida Tripodi, Gabriella Tedeschi, Simona Nonnis, Oriano Marin, Sonia Fantinato, Claudia Cirulli, Marco Vanoni and Lilia Alberghina

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The ubiquitin-conjugating enzyme Cdc34 was recently shown to be phosphorylated by CK2 on the C-terminal tail. Here we present novel findings indicating that in budding yeast CK2 phosphorylates Cdc34 within the N-terminal catalytic domain. Specifically, we show, by direct mass spectrometry analysis, that Cdc34 is phosphorylated in vitro and in vivo by CK2 on Ser130 and Ser167, and that the phosphoserines 130 and 167 are not present after CK2 inactivation in a cka1Δcka2-8ts strain. CK2 phosphorylation of Ser130 and Ser167 strongly stimulates Cdc34 ubiquitin charging in vitro. The Cdc34S130AS167A mutant shows a basal ubiquitin charging activity which is indistinguishable from that of wild type but is not activated by CK2 phosphorylation and its expression fails to complement a cdc34-2ts yeast strain, supporting a model in which activation of Cdc34 involves CK2-mediated phosphorylation of its catalytic domain.

Authors

Paola Coccetti

University of Milano-Bicocca; Milano, Italy

Farida Tripodi

University of Milano-Bicocca; Milano, Italy

Gabriella Tedeschi

University of Milano; Milano, Italy

Simona Nonnis

University of Milano; Milano, Italy

Oriano Marin

University of Padova; Padova, Italy

Sonia Fantinato

University of Milano-Bicocca; Milano, Italy

Claudia Cirulli

University of Milano-Bicocca; Milano, Italy

Marco Vanoni

University of Milano-Bicocca; Milano, Italy

Lilia Alberghina

University of Milano-Bicocca; Milano, Italy

Purchase article for $19

Subscribe to this journal for $129/year