DNA damage inhibits proteolysis of the B-type cyclin Clb5 in S. cerevisiae

Doris Germain, Joy Hendley, Bruce Futcher

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13 Scopus citations


Cell cycle progression is mediated by waves of specific cyclin dependent kinases (CDKs) in all eukaryotes. Cyclins are degraded by the ubiquitin pathway of proteolysis. The recent identification of several components of the cyclin proteolysis machinery has highlighted both the importance of proteolysis at multiple transition points in the cell cycle and the involvement of other substrates degraded by the same machinery. In this study, we have investigated the effects of DNA damage on the cyclin proteolytic machinery in Saccharomyces cerevisiae. We find that the half-life of the B-type cyclin Clb5 is markedly increased following DNA damage while that of G1 cyclins is not. This effect is independent of cell cycle phase. Clb5 turnover requires p34(CDC28) activity. Stabilisation of Clb5 correlates with an increase in tyrosine phosphorylation of p34(CDC28), but stabilisation does not require this tyrosine phosphorylation. The stabilisation is independent of the checkpoint genes Mec1 and Rad53. These observations establish a new link between the regulation of proteolysis and DNA damage.

Original languageEnglish
Pages (from-to)1813-1820
Number of pages8
JournalJournal of Cell Science
Issue number15
StatePublished - Aug 1997
Externally publishedYes


  • Budding yeast
  • Cyclin
  • DNA damage
  • Ubiquitin dependent proteolysis


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