Error rate and specificity of human and murine DNA polymerase η
Error rate and specificity of human and murine DNA polymerase η
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DOI：
10.1006/jmbi.2001.4937
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发表时间：
2001-09-14
影响因子：
5.6
通讯作者：
Kunkel, TA
中科院分区：
文献类型：
--
作者：
Matsuda, T;Bebenek, K;Kunkel, TA
我们在此描述哺乳动物DNA聚合酶η（pol η）的错误特异性，该酶进行跨损伤DNA合成，并可能参与免疫球蛋白基因的体细胞高频突变。小鼠和人类的pol η都缺乏内在的校对核酸外切酶活性，并且两者对未受损DNA的复制都不准确。对人类pol η产生的1500多个单碱基替换的分析表明，所有12种错配的错误率都很高且因错配的组成、对称性及其位置而异。pol η还以前所未有的速率产生串联碱基替换，并且动力学分析表明，它延伸串联双错配的效率与其他复制酶延伸单碱基错配的效率大致相同。这种使用异常引物末端的能力以及高的单碱基和双碱基替换率支持这样一种观点，即pol η可能放弃严格的形状互补性以促进高效的损伤旁路。pol η对多种核苷酸缺失和添加错误的不忠实性进一步表明其辨别力宽松。这些错误的性质和位置表明，有些可能是由链滑动引发的，而其他则是由其他机制导致的。
We describe here the error specificity of mammalian DNA polymerase eta (pol eta), an enzyme that performs translesion DNA synthesis and may participate in somatic hypermutation of immunoglobulin genes. Both mouse and human pol eta lack intrinsic proofreading exonuclease activity and both copy undamaged DNA inaccurately. Analysis of more than 1500 single-base substitutions by human pol eta indicates that error rates for all 12 mismatches are high and variable depending on the composition and symmetry of the mismatch and its location. pol eta also generates tandem base substitutions at an unprecedented rate, and kinetic analysis indicates that it extends a tandem double mismatch about as efficiently as other replicative enzymes extend single-base mismatches. This ability to use an aberrant primer terminus and the high rate of single and double-base substitutions support the idea that pol eta may forego strict shape complementarity in order to facilitate highly efficient lesion bypass. Relaxed discrimination is further indicated by pol eta infidelity for a wide variety of nucleotide deletion and addition errors. The nature and location of these errors suggest that some may be initiated by strand slippage, while others result from additional mechanisms.