title: Yeast Hct1 is a regulator of Clb2 cyclin proteolysis.
abstract: Stage-specific proteolysis of mitotic cyclins is fundamental to eukaryotic cell cycle regulation. We found that yeast Hct1, a conserved protein of eukaryotes, is a necessary and rate-limiting component of this proteolysis pathway. In hct1 mutants, the mitotic cyclin Clb2 is highly stabilized and inappropriately induces DNA replication, while G1 cyclins and other proteolytic substrates remain short-lived. Viability of hct1 mutants depends on SIC1. This and further results suggest that inhibition of cyclin-dependent kinases may compensate for defects in cyclin proteolysis. Remarkably, elevated levels of Hct1 ectopically activate destruction box- and Cdc23-dependent degradation of Clb2 and cause phenotypic effects characteristic for a depletion of M-phase cyclins. Hct1 and the related Cdc20 may function as substrate-specific regulators of proteolysis during mitosis.
authors.affiliation: Institute of Industrial Genetics, University of Stuttgart, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Schwab
authors.forename: A S
authors.initials: AS
authors.lastname: Lutum
authors.forename: W
authors.initials: W
authors.lastname: Seufert
mesh_terms: D000595:Amino Acid Sequence; D064173:Anaphase-Promoting Complex-Cyclosome; D064196:Apc8 Subunit, Anaphase-Promoting Complex-Cyclosome; D064199:Cdc20 Proteins; D064200:Cdh1 Proteins; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D019926:Cyclin B; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors; D016213:Cyclins / Q000378:metabolism*; D015536:Down-Regulation; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D018628:Gene Dosage; D008938:Mitosis; D008969:Molecular Sequence Data; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D043743:Ubiquitin-Protein Ligase Complexes
chemical_list: D064196:Apc8 Subunit, Anaphase-Promoting Complex-Cyclosome; C577495:CDC20 protein, S cerevisiae; C577441:CDC23 protein, S cerevisiae; C577583:CDH1 protein, S cerevisiae; C093749:CLB2 protein, S cerevisiae; D064199:Cdc20 Proteins; D064200:Cdh1 Proteins; D018797:Cell Cycle Proteins; D019926:Cyclin B; D016213:Cyclins; D005656:Fungal Proteins; D029701:Saccharomyces cerevisiae Proteins; D043743:Ubiquitin-Protein Ligase Complexes; D064173:Anaphase-Promoting Complex-Cyclosome; D018844:Cyclin-Dependent Kinases