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Priority Report

The Crystal Structure of Human Cyclin B

Edward T. Petri, Alessia Errico, Lourdes Escobedo, Tim Hunt and Ravi Basavappa

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Cyclin B is the key regulatory protein controlling mitosis in all eukaryotes, where it binds cyclin-dependent kinase, cdk1, forming a complex which initiates the mitotic program through phosphorylation of select proteins. Cyclin B regulates the activation, subcellular localization, and substrate specificity of cdk1, and destruction of cyclin B is necessary for mitotic exit. Overexpression of human cyclin B1 has been found in numerous cancers and has been associated with tumor aggressiveness. Here we report the crystal structure of human cyclin B1 to 2.9 Å. Comparison of the structure with cyclin A and cyclin E reveals remarkably similar N-terminal cyclin box motifs but significant differences among the C-terminal cyclin box lobes. Divergence in sequence gives rise to unique interaction surfaces at the proposed cyclin B/ cdk1 interface as well as the ‘RxL’ motif substrate binding site on cyclin B. Examination of the structure provides insight into the molecular basis for differential affinities of protein based cyclin/cdk inhibitors such as p27, substrate recognition, and cdk interaction.

Authors

Edward T. Petri

University of Rochester, Rochester, New York

Alessia Errico

Clare Hall Laboratories, Herts, England UK

Lourdes Escobedo

University of Rochester, Rochester, New York

Tim Hunt

Cancer Research UK, Herts, England UK

Ravi Basavappa

University of Rochester, Rochester, New York

Purchase article for $19

Subscribe to this journal for $129/year