DNA damage inhibits proteolysis of the B-type cyclin Clb5 in S. cerevisiae.
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 p34CDC28 activity. Stabilisation of Clb5 correlates with an increase in tyrosine phosphorylation of p34CDC28, 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.
Germain
D
D
Trescowthick Research Laboratories, Peter MacCallum Cancer Institute, Melbourne, Victoria, Australia. germain@petermac.unimelb.edu.au
Hendley
J
J
Futcher
B
B
D017489:CDC28 Protein Kinase, S cerevisiae / Q000378:metabolism; D002453:Cell Cycle; D018797:Cell Cycle Proteins; D064447:Checkpoint Kinase 2; D019926:Cyclin B; D050756:Cyclin-Dependent Kinase Inhibitor Proteins; D016213:Cyclins / Q000235:genetics / Q000378:metabolism*; D004249:DNA Damage; D004271:DNA, Fungal / Q000187:drug effects / Q000528:radiation effects; D005656:Fungal Proteins / Q000378:metabolism* / Q000502:physiology; D006207:Half-Life; D047908:Intracellular Signaling Peptides and Proteins; D009154:Mutation; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases; D016196:S Phase; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins
C076558:CLB5 protein, S cerevisiae; C082721:CLN2 protein, S cerevisiae; D018797:Cell Cycle Proteins; D019926:Cyclin B; D050756:Cyclin-Dependent Kinase Inhibitor Proteins; D016213:Cyclins; D004271:DNA, Fungal; D005656:Fungal Proteins; D047908:Intracellular Signaling Peptides and Proteins; C086926:SIC1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D019000:Phosphotyrosine; D011494:Protein Kinases; D064447:Checkpoint Kinase 2; C088937:MEC1 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases; D017489:CDC28 Protein Kinase, S cerevisiae; C067022:RAD53 protein, S cerevisiae