Department of Biochemistry, King's College London, UK.
Biochem J. 2010 Mar 29;427(2):225-36. doi: 10.1042/BJ20091888.
To assess the potential of mutations from the L1 loop of the tumour suppressor p53 as second-site suppressors, the effect of H115N and S116M on the p53 'hot spot' mutations has been investigated using the double-mutant approach. The effects of these two mutants on the p53 hot spots in terms of thermal stability and DNA binding were evaluated. The results show that: (i) the p53 mutants H115N and S116M are thermally more stable than wild-type p53; (ii) H115N but not S116M is capable of rescuing the DNA binding of one of the most frequent p53 mutants in cancer, R248Q, as shown by binding of R248Q/H115N to gadd45 (the promoter of a gene involved in cell-cycle arrest); (iii) the double mutant R248Q/H115N is more stable than wild-type p53; (iv) the effect of H115N as a second-site suppressor to restore DNA-binding activity is specific to R248Q, but not to R248W; (v) molecular-dynamics simulations indicate that R248Q/H115N has a conformation similar to wild-type p53, which is distinct from that of R248Q. These findings could be exploited in designing strategies for cancer therapy to identify molecules that could mimic the effect of H115N in restoring function to oncogenic p53 mutants.
为了评估肿瘤抑制因子 p53 的 L1 环突变作为第二部位抑制子的潜力，采用双突变体方法研究了 H115N 和 S116M 对 p53“热点”突变的影响。评估了这两种突变体对 p53 热点在热稳定性和 DNA 结合方面的影响。结果表明：（i）p53 突变体 H115N 和 S116M 比野生型 p53 更热稳定；（ii）H115N 但不是 S116M 能够拯救癌症中最常见的 p53 突变体之一 R248Q 的 DNA 结合，如 R248Q/H115N 与 gadd45（参与细胞周期停滞的基因的启动子）结合所示；（iii）双突变体 R248Q/H115N 比野生型 p53 更稳定；（iv）H115N 作为第二部位抑制子恢复 DNA 结合活性的作用是特定于 R248Q 的，而不是 R248W 的；（v）分子动力学模拟表明，R248Q/H115N 具有与野生型 p53 相似的构象，与 R248Q 不同。这些发现可用于设计癌症治疗策略，以鉴定能够模拟 H115N 恢复致癌 p53 突变体功能的分子。
