2cci

File:2cci.gif

spinqualitylabelsall models 2cci, resolution 2.70Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

CRYSTAL STRUCTURE OF PHOSPHO-CDK2 CYCLIN A IN COMPLEX WITH A PEPTIDE CONTAINING BOTH THE SUBSTRATE AND RECRUITMENT SITES OF CDC6

OverviewOverview

Phospho-CDK2/cyclin A, a kinase that is active in cell cycle S phase, contains an RXL substrate recognition site that is over 40 A from the, catalytic site. The role of this recruitment site, which enhances, substrate affinity and catalytic efficiency, has been investigated using, peptides derived from the natural substrates, namely CDC6 and p107, and a, bispeptide inhibitor in which the gamma-phosphate of ATP is covalently, attached by a linker to the CDC6 substrate peptide. X-ray studies with a, 30-residue CDC6 peptide in complex with pCDK2/cyclin A showed binding of a, dodecamer peptide at the recruitment site and a heptapeptide at the, catalytic site, but no density for the linking 11 residues. Kinetic, studies established that the CDC6 peptide had an 18-fold lower Km compared, with heptapeptide substrate and that this effect required the recruitment, peptide to be covalently linked to the substrate peptide. X-ray studies, with the CDC6 bispeptide showed binding of the dodecamer at the, recruitment site and the modified ATP in two alternative conformations at, the catalytic site. The CDC6 bispeptide was a potent inhibitor competitive, with both ATP and peptide substrate of pCDK2/cyclin A activity against a, heptapeptide substrate (Ki = 0.83 nm) but less effective against, RXL-containing substrates. We discuss how localization at the recruitment, site (KD 0.4 microm) leads to increased catalytic efficiency and the, design of a potent inhibitor. The notion of a flexible linker between the, sites, which must have more than a minimal number of residues, provides an, explanation for recognition and discrimination against different, substrates.

About this StructureAbout this Structure

2CCI is a Protein complex structure of sequences from Homo sapiens with and as ligands. Active as Transferred entry: 2.7.11.1, with EC number 2.7.1.37 Known structural/functional Site: . Full crystallographic information is available from OCA.

ReferenceReference

The role of the phospho-CDK2/cyclin A recruitment site in substrate recognition., Cheng KY, Noble ME, Skamnaki V, Brown NR, Lowe ED, Kontogiannis L, Shen K, Cole PA, Siligardi G, Johnson LN, J Biol Chem. 2006 Aug 11;281(32):23167-79. Epub 2006 May 17. PMID:16707497

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