MOLECULAR DYNAMICS STUDY OF RADIOSENSITIVE MUTANT ALLELE OF PROTEIN KINASE ycdc28-srm G20S USING hcdk2 AS MODEL

摘要

The cyclin-dependent kinases play an essential role in the timing of cell division and repair, furthermore a high incidence of genetic alterations of CDKs or deregulation of CDK inhibitors have been observed in several cancers. These arguments make of CDC28 of Saccharomyces cerevisiae yeast a very attractive model to study CDK regulation mechanisms. We observed certain gene mutations, including cdc28-srm [G20S], affect cell cycle progression, maintenance of different genetic structures (Devin, 1990), checkpoint-control (Li, 1997) and increase cell radiosensitivity (Koltovaya, 1998). A cdc28-srm mutation is not a temperature-sensitive mutation and differs from known cdc28-ts mutations, since it shows the evident phenotypic manifestations at 30°C. The mutation is on the third glycine site in the conserved sequence GxGxxG of the G-rich loop, whose position is opposite to the activation T-loop. Despite its established importance, the role of the G-loop is still unclear. The crystal structure of the human CDK2 served as model for the catalytic core of other CDKs, including CDC28. Nanoseconds long molecular dynamics trajectories of the CDK2/ATP complex were analysed. The MD simulations of corresponded substitution CDK2-G16S in conserved G-loop shows this amino acid importance and the induced conformational change in CDK2 structure, resulting in the ATP removal from G-loop and in new amino acids rearrangement in the T-loop.