title: The cyclin A centrosomal localization sequence recruits MCM5 and Orc1 to regulate centrosome reduplication.
abstract: Centrosomes are the major microtubule-organizing centers in animal cells and regulate formation of a bipolar mitotic spindle. Aberrant centrosome number causes chromosome mis-segregation, and has been implicated in genomic instability and tumor development. Previous studies have demonstrated a role for the DNA replication factors MCM5 and Orc1 in preventing centrosome reduplication. Cyclin A-Cdk2 localizes on centrosomes by means of a modular centrosomal localization sequence (CLS) that is distinct from that of cyclin E. Here, we show that cyclin A interacts with both MCM5 and Orc1 in a CLS-dependent but Cdk-independent manner. Although the MRAIL hydrophobic patch is contained within the cyclin A CLS, binding of both MCM5 and Orc1 to cyclin A does not require a wild-type hydrophobic patch. The same domain in MCM5 that mediates interaction with cyclin E also binds cyclin A, resulting in centrosomal localization of MCM5. Finally, unlike its function in DNA synthesis, MCM5-mediated inhibition of centrosome reduplication in S-phase-arrested CHO cells does not require binding to other MCM family members. These results suggest that cyclins E and A sequentially prevent centrosome reduplication throughout interphase by recruitment of DNA replication factors such as MCM5 and Orc1.
authors.affiliation: Howard Hughes Medical Institute and Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO 80045, USA.
authors.forename: Rebecca L
authors.initials: RL
authors.lastname: Ferguson
authors.forename: Gaetan
authors.initials: G
authors.lastname: Pascreau
authors.forename: James L
authors.initials: JL
authors.lastname: Maller
mesh_terms: D000818:Animals; D016466:CHO Cells; D018797:Cell Cycle Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D018385:Centrosome / Q000378:metabolism / Q000502:physiology*; D006224:Cricetinae; D003412:Cricetulus; D019925:Cyclin A / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D005455:Fluorescent Antibody Technique; D006367:HeLa Cells; D006801:Humans; D047468:Immunoprecipitation; D022101:Microtubule-Organizing Center / Q000378:metabolism; D051738:Origin Recognition Complex / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D014162:Transfection
chemical_list: D018797:Cell Cycle Proteins; D019925:Cyclin A; C489423:MCM5 protein, human; C497223:ORC1 protein, human; D051738:Origin Recognition Complex