Specificity Determinants of Recruitment Peptides Bound to Phospho-CDK2/Cyclin A
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- 作者：Edward D. Lowe ; Ivo Tews ; Kin Yip Cheng ; Nick R. Brown ; Sheraz Gul ; Martin E. M. Noble ; Steven J. Gamblin ; and Louise N. Johnson
- 刊名：Biochemistry
- 出版年：2002
- 出版时间：December 31, 2002
- 年：2002
- 卷：41
- 期：52
- 页码：15625 - 15634
- 全文大小：611K
- 年卷期：v.41,no.52(December 31, 2002)
- ISSN：1520-4995
文摘
Progression through S phase of the eukaryotic cell cycle is regulated by the action of thecyclin dependent protein kinase 2 (CDK2) in association with cyclin A. CDK2/cyclin A phosphorylatesnumerous substrates. Substrate specificity often employs a dual recognition strategy in which the sequenceflanking the phospho-acceptor site (Ser.Pro.X.Arg/Lys) is recognized by CDK2, while the cyclin Acomponent 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 Å resolution and isothermal calorimetrymeasurements on complexes of phospho-CDK2/cyclin A with a recruitment peptide derived from E2F1and with shorter 11-mer peptides from p53, pRb, p27, E2F1, and p107. The results show that the cyclinrecruitment site accommodates a second hydrophobic residue either immediately C-terminal or next adjacentto the leucine of the "RXL" motif and that this site makes important contributions to the recruitmentpeptide recognition. The arginine of the RXL motif contacts a glutamate, Glu220, on the cyclin. In thosesubstrates that contain a KXL motif, no ionic interactions are observed with the lysine. The sequencesN-terminal to the "RXL" motif of the individual peptides show no conservation, but nevertheless makecommon contacts to the cyclin through main chain interactions. Thus, the recruitment site is able torecognize diverse but conformationally constrained target sequences. The observations have implicationsfor the further identification of physiological substrates of CDK2/cyclin A and the design of specificinhibitors.