Cyclin A2 mutagenesis analysis: a new insight into CDK activation and cellular localization requirements

PLoS One. 2011;6(7):e22879. doi: 10.1371/journal.pone.0022879. Epub 2011 Jul 28.


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 α helix, in conjunction with the α3 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Blotting, Western
  • CDC2 Protein Kinase / metabolism*
  • Cell Nucleus / metabolism*
  • Cells, Cultured
  • Cyclin A2 / genetics*
  • Cyclin A2 / metabolism
  • Cyclin-Dependent Kinase 2 / metabolism*
  • Cyclin-Dependent Kinase Inhibitor p21 / metabolism
  • Cyclin-Dependent Kinase Inhibitor p27 / metabolism
  • Embryo, Mammalian / cytology
  • Embryo, Mammalian / metabolism
  • Fibroblasts / cytology
  • Fibroblasts / metabolism
  • Fluorescent Antibody Technique
  • Immunoprecipitation
  • Mice
  • Mice, Knockout
  • Mutagenesis, Site-Directed
  • Mutation / genetics*
  • NIH 3T3 Cells
  • Retinoblastoma-Like Protein p107 / metabolism


  • CCNA2 protein, mouse
  • Cdkn1a protein, mouse
  • Cdkn1b protein, mouse
  • Cyclin A2
  • Cyclin-Dependent Kinase Inhibitor p21
  • Rbl1 protein, mouse
  • Retinoblastoma-Like Protein p107
  • Cyclin-Dependent Kinase Inhibitor p27
  • CDC2 Protein Kinase
  • Cdk2 protein, mouse
  • Cyclin-Dependent Kinase 2