1h25

From Proteopedia

Revision as of 10:56, 21 February 2008

CDK2/CYCLIN A IN COMPLEX WITH AN 11-RESIDUE RECRUITMENT PEPTIDE FROM RETINOBLASTOMA-ASSOCIATED PROTEIN

Overview

Progression through S phase of the eukaryotic cell cycle is regulated by the action of the cyclin dependent protein kinase 2 (CDK2) in association with cyclin A. CDK2/cyclin A phosphorylates numerous substrates. Substrate specificity often employs a dual recognition strategy in which the sequence flanking the phospho-acceptor site (Ser.Pro.X.Arg/Lys) is recognized by CDK2, while the cyclin A component of the complex contains a hydrophobic site that binds Arg/Lys.X.Leu ("RXL" or "KXL") substrate recruitment motifs. To determine additional sequence specificity motifs around the RXL sequence, we have performed X-ray crystallographic studies at 2.3 A resolution and isothermal calorimetry measurements on complexes of phospho-CDK2/cyclin A with a recruitment peptide derived from E2F1 and with shorter 11-mer peptides from p53, pRb, p27, E2F1, and p107. The results show that the cyclin recruitment site accommodates a second hydrophobic residue either immediately C-terminal or next adjacent to the leucine of the "RXL" motif and that this site makes important contributions to the recruitment peptide recognition. The arginine of the RXL motif contacts a glutamate, Glu220, on the cyclin. In those substrates that contain a KXL motif, no ionic interactions are observed with the lysine. The sequences N-terminal to the "RXL" motif of the individual peptides show no conservation, but nevertheless make common contacts to the cyclin through main chain interactions. Thus, the recruitment site is able to recognize diverse but conformationally constrained target sequences. The observations have implications for the further identification of physiological substrates of CDK2/cyclin A and the design of specific inhibitors.

Disease

Known diseases associated with this structure: Bladder cancer OMIM:[180200], Osteosarcoma OMIM:[180200], Pinealoma with bilateral retinoblastoma OMIM:[180200], Retinoblastoma OMIM:[180200]

About this Structure

1H25 is a Protein complex structure of sequences from Homo sapiens. Full crystallographic information is available from OCA.

Reference

Specificity determinants of recruitment peptides bound to phospho-CDK2/cyclin A., Lowe ED, Tews I, Cheng KY, Brown NR, Gul S, Noble ME, Gamblin SJ, Johnson LN, Biochemistry. 2002 Dec 31;41(52):15625-34. PMID:12501191

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