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Priority Report

Cyclin B and Cyclin A Confer Different Substrate Recognition Properties on CDK2

Nick R. Brown, Ed D. Lowe, Ed Petri, Vicky Skamnaki, Robin Antrobus and Louise Johnson

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The transitions of the cell cycle are regulated by the cyclin dependent protein kinases (CDKs). The cyclins activate their respective CDKs and confer substrate recognition properties. We report the structure of phospho-CDK2/cyclin B and show that cyclin B confers M phase-like properties on CDK2, the kinase that is usually associated with S phase. Cyclin B produces an almost identical activated conformation of CDK2 as that produced by cyclin A. There are differences between cyclin A and cyclin B at the recruitment site, which in cyclin A is used to recruit substrates containing an RXL motif. Because of sequence differences this site in cyclin B binds RXL motifs more weakly than in cyclin A. Despite similarity in kinase structures, phospho-CDK2/cyclin B phosphorylates substrates, such as nuclear lamin and a model peptide derived from p107, at sequences SPXX that differ from the canonical CDK2/cyclin A substrate recognition motif, SPXK. CDK2/cyclin B phosphorylation at these non-canonical sites is not dependent on the presence of a RXL recruitment motif. The p107 peptide contained two SP motifs each followed by a noncanonical sequence of which only one site (Ser640) is phosphorylated by pCDK2/cyclin A while two sites are phosphorylated by pCDK2/cyclin B. The second site is too close to the RXL motif to allow the cyclin A recruitment site to be effective, as previous work has shown that there must be at least 16 residues between the catalytic site serine and the RXL motif. Thus the cyclins A and B in addition to their role in promoting the activatory conformational switch in CDK2, also provide differential substrate specificity.

Authors

Nick R. Brown

University of Oxford, Oxford, UK

Ed D. Lowe

University of Oxford, Oxford, UK

Ed Petri

University of Rochester, Rochester, New York

Vicky Skamnaki

National Hellenic Research Foundation, Athens, Greece

Robin Antrobus

University of Oxford, Oxford, UK

Louise Johnson

University of Oxford; Oxford UK

This is an open-access article

 Download PDF

If the document does not open, please right-click on the link (control-click on a Macintosh) and select the option to save the file to disk.