title: Degradation of origin recognition complex large subunit by the anaphase-promoting complex in Drosophila.
abstract: The initiation of DNA synthesis is thought to occur at sites bound by a heteromeric origin recognition complex (ORC). Previously, we have shown that in Drosophila, the level of the large subunit, ORC1, is modulated during cell cycle progression and that changes in ORC1 concentration alter origin utilization during development. Here, we investigate the mechanisms underlying cell cycle-dependent degradation of ORC1. We show that signals in the non-conserved N-terminal domain of ORC1 mediate its degradation upon exit from mitosis and in G1 phase by the anaphase-promoting complex (APC) in vivo. Degradation appears to be the result of direct action of the APC, as the N-terminal domain is ubiquitylated by purified APC in vitro. This regulated proteolysis is potent, sufficient to generate a normal temporal distribution of protein even when transcription of ORC1 is driven by strong constitutive promoters. These observations suggest that in Drosophila, ORC1 regulates origin utilization much as does Cdc6 in budding yeast.
authors: Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA.
authors: Marito
authors: M
authors: Araki
authors: Robin P
authors: RP
authors: Wharton
authors: Zhanyun
authors: Z
authors: Tang
authors: Hongtao
authors: H
authors: Yu
authors: Maki
authors: M
authors: Asano
mesh_terms: D064173:Anaphase-Promoting Complex-Cyclosome; D000818:Animals; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004330:Drosophila / Q000196:embryology / Q000378:metabolism*; D029721:Drosophila Proteins; D005123:Eye / Q000196:embryology; D016193:G1 Phase / Q000502:physiology; D008938:Mitosis / Q000502:physiology*; D051738:Origin Recognition Complex; D043743:Ubiquitin-Protein Ligase Complexes / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; C497213:Orc1 protein, Drosophila; D051738:Origin Recognition Complex; D043743:Ubiquitin-Protein Ligase Complexes; D064173:Anaphase-Promoting Complex-Cyclosome