Recognition and binding of mismatch repair proteins at an oncogenic hot spot.
Recognition and binding of mismatch repair proteins at an oncogenic hot spot.
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DOI：
10.1186/1471-2199-6-6
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发表时间：
2005-03-14
影响因子：
--
通讯作者：
Williams KJ
中科院分区：
文献类型：
--
作者：
Edelbrock M;He H;Schroering A;Fernstrom M;Bathala S;Williams KJ
目前的研究是为了确定区分核环境中H-ras致癌热点的G：T和G：A修复的关键步骤，因为这两种错配的修复效率存在很大差异。电泳迁移率变动（凝胶位移）实验表明，含有错配碱基的DNA在MMR有效和MMR缺陷（hMLH 1-/-）核提取物中被hMutSα识别和结合的效率相同。竞争实验表明，虽然hMutSα可预测地结合G：T错配的程度比G：A大得多，但hMutSα在H-ras突变热点处对G：T和G：A错配结合反应的竞争性抑制比例惊人地相等。此外，错配修复测定揭示了与G：T总体修复相比，总体G：A修复的效率几乎高2倍（5 '-切口定向的对G：C的正确MMR和对T：A的不正确修复）。而G：T → G：C的正确MMR（96%）显著高于G：A → G：C（60%）。结合起来，这些结果表明，正确的MMR的启动需要两个独立的步骤的贡献; hMutSα的初始识别，随后是随后的结合。结合步骤的“亲合力”决定了MMR途径活化的程度，或不同细胞途径的活化。因此，hMutSα的初始识别结合随后与G：A错配结合的降低（与G：T相比）可能导致观察到的G：A错误修复频率增加，导致在高比例的人类肿瘤中发现的主要GGC → GTC（Gly →瓦尔）ras激活突变。
The current investigation was undertaken to determine key steps differentiating G:T and G:A repair at the H-ras oncogenic hot spot within the nuclear environment because of the large difference in repair efficiency of these two mismatches. Electrophoretic mobility shift (gel shift) experiments demonstrate that DNA containing mismatched bases are recognized and bound equally efficiently by hMutSα in both MMR proficient and MMR deficient (hMLH1-/-) nuclear extracts. Competition experiments demonstrate that while hMutSα predictably binds the G:T mismatch to a much greater extent than G:A, hMutSα demonstrates a surprisingly equal ratio of competitive inhibition for both G:T and G:A mismatch binding reactions at the H-ras hot spot of mutation. Further, mismatch repair assays reveal almost 2-fold higher efficiency of overall G:A repair (5'-nick directed correct MMR to G:C and incorrect repair to T:A), as compared to G:T overall repair. Conversely, correct MMR of G:T → G:C is significantly higher (96%) than that of G:A → G:C (60%). Combined, these results suggest that initiation of correct MMR requires the contribution of two separate steps; initial recognition by hMutSα followed by subsequent binding. The 'avidity' of the binding step determines the extent of MMR pathway activation, or the activation of a different cellular pathway. Thus, initial recognition by hMutSα in combination with subsequent decreased binding to the G:A mismatch (as compared to G:T) may contribute to the observed increased frequency of incorrect repair of G:A, resulting in the predominant GGC → GTC (Gly → Val) ras-activating mutation found in a high percentage of human tumors.
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影响因子：
16
作者：
Junop, MS;Obmolova, G;Yang, W
通讯作者：
Yang, W
影响因子：
4
作者：
Fishel, R;Wilson, T
通讯作者：
Wilson, T
影响因子：
56.9
作者：
DRUMMOND, JT;LI, GM;MODRICH, P
通讯作者：
MODRICH, P
影响因子：
4.8
作者：
Chang, DK;Ricciardiello, L;Boland, CR
通讯作者：
Boland, CR
影响因子：
4.7
作者：
Arcangeli, L;Simonetti, J;Williams, KJ
通讯作者：
Williams, KJ