Cyclin A2 is essential at two critical points in the somatic cell cycle: during S phase, when it activates CDK2, and during the G2 to M transition when it activates CDK1. Based on the crystal structure of Cyclin A2 in association with CDKs, we generated a panel of mutants to characterize the specific amino acids required for partner binding, CDK activation and subcellular localization. We find that CDK1, CDK2, p21, p27 and p107 have overlapping but distinct requirements for association with this protein. Our data highlight the crucial importance of the N-terminal alpha helix, in conjunction with the alpha3 helix within the cyclin box, in activating CDK. Several Cyclin A2 mutants selectively bind to either CDK1 or CDK2. We demonstrate that association of Cyclin A2 to proteins such as CDK2 that was previously suggested as crucial is not a prerequisite for its nuclear localization, and we propose that the whole protein structure is involved.
Cyclin A2 mutagenesis analysis: a new insight into CDK activation and cellular localization requirements
Bendris, N.; Lemmers, B.; Blanchard, J. M.; Arsic, N.
2011 / vol 6 / pages e22879
10.1371/journal.pone.0022879 PONE-D-11-07933 [pii]
1932-6203 (Electronic) 1932-6203 (Linking)
Animals; Cells, Cultured; Mice; Mice, Knockout; NIH 3T3 Cells; Fibroblasts/cytology/metabolism; Immunoprecipitation; Blotting, Western; Fluorescent Antibody Technique; Mutagenesis, Site-Directed; CDC2 Protein Kinase/*metabolism; Cyclin-Dependent Kinase 2/*metabolism; Embryo, Mammalian/cytology/metabolism; Cell Nucleus/*metabolism; Cyclin A2/*genetics/metabolism; Cyclin-Dependent Kinase Inhibitor p21/metabolism; Cyclin-Dependent Kinase Inhibitor p27/metabolism; Mutation/*genetics; Retinoblastoma-Like Protein p107/metabolism