Two different modes of cyclin clb2 proteolysis during mitosis in Saccharomyces cerevisiae.
Sister chromatid separation and mitotic exit are triggered by the anaphase-promoting complex (APC/C) which is a multi-subunit ubiquitin ligase required for proteolytic degradation of various target proteins. Cdc20 and Cdh1 are substrate-specific activators of the APC/C. It was previously proposed that Cdh1 is essential for proteolysis of the yeast mitotic cyclin Clb2. We show that Clb2 proteolysis is triggered by two different modes during mitosis. A fraction of Clb2 is degraded during anaphase in the absence of Cdh1. However, a second fraction of Clb2 remains stable during anaphase and is degraded in a Cdh1-dependent manner as cells exit from mitosis. Most of cyclin Clb3 is degraded independently of Cdh1. Our data imply that degradation of mitotic cyclins is initiated by a Cdh1-independent mechanism.
Bäumer
M
M
Institute of Microbiology and Genetics, Georg-August-University, Grisebachstrasse 8, D-37077, Göttingen, Germany.
Braus
G H
GH
Irniger
S
S
D064173:Anaphase-Promoting Complex-Cyclosome; D064200:Cdh1 Proteins; D002453:Cell Cycle / Q000502:physiology*; D019926:Cyclin B / Q000235:genetics / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D016193:G1 Phase; D008025:Ligases / Q000378:metabolism; D008938:Mitosis; D008954:Models, Biological; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins; D043743:Ubiquitin-Protein Ligase Complexes; D044767:Ubiquitin-Protein Ligases
C577583:CDH1 protein, S cerevisiae; C093749:CLB2 protein, S cerevisiae; D064200:Cdh1 Proteins; D019926:Cyclin B; D005656:Fungal Proteins; D029701:Saccharomyces cerevisiae Proteins; D043743:Ubiquitin-Protein Ligase Complexes; D064173:Anaphase-Promoting Complex-Cyclosome; D044767:Ubiquitin-Protein Ligases; D008025:Ligases