Structural studies with inhibitors of the cell cycle regulatory kinase cyclin-dependent protein kinase 2.
Components of the cell cycle machinery are frequently altered in cancer. Many of these alterations affect the cyclin-dependent kinases (CDKs) and their regulation. Staurosporine and 7-hydroxystaurosporine (UCN-01) are two natural product kinase inhibitors originally identified as potent protein kinase C inhibitors. Staurosporine is non-selective and too toxic for use in therapy, but UCN-01 shows greater selectivity, and is in clinical trials. We have determined the crystal structures of staurosporine bound to monomeric CDK2 and UCN-01 bound to active phospho-CDK2/cyclin A. Both compounds mimic the hydrogen bonds made by the adenine moiety of ATP, and both exploit the non-polar nature of the adenine-binding site. In the complex with UCN-01, a hydrogen-bonded water molecule is incorporated into the non-polar cavity, which provides a partial polar character in the environment of the 7-hydroxyl group. Comparison of the ATP-binding site of CDK2 with that of other kinases reveals that in Chk1 kinase, a major target for UCN-01 in the cell, one of the surrounding residues, Ala144 in CDK2, is a serine in Chk1, thus providing a possible explanation for the effectiveness of UCN-01 against this kinase. For cells to exit mitosis, the CDKs must be completely inactivated, firstly by the ubiquintin-mediated destruction of the cyclins, followed by dephosphorylation of phospho-Thr160 (in CDK2) catalysed by the kinase-associated phosphatase and protein phosphatase 2C. We describe the structure of phospho-CDK2 in complex with kinase-associated phosphatase, and discuss the substrate recognition promoted by interactions that are remote from the catalytic site.
Johnson
Louise N
LN
Laboratory of Molecular Biophysics, Department of Biochemistry, University of Oxford, Rex Richards Building, South Parks Road, OX1 3QU, Oxford, UK. louise@biop.ox.ac.uk
De Moliner
Erika
E
Brown
Nick R
NR
Song
Haiwei
H
Barford
David
D
Endicott
Jane A
JA
Noble
Martin E M
ME
D042846:CDC2-CDC28 Kinases; D051357:Cyclin-Dependent Kinase 2; D050759:Cyclin-Dependent Kinase Inhibitor p21; D018844:Cyclin-Dependent Kinases / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D016213:Cyclins / Q000378:metabolism / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000378:metabolism / Q000494:pharmacology*; D006801:Humans; D008967:Molecular Biology; D009369:Neoplasms / Q000188:drug therapy / Q000201:enzymology / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D019311:Staurosporine / Q000378:metabolism / Q000494:pharmacology*; D013329:Structure-Activity Relationship
C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D004791:Enzyme Inhibitors; D017346:Protein Serine-Threonine Kinases; D042846:CDC2-CDC28 Kinases; C495894:CDK2 protein, human; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases; D019311:Staurosporine