Unusual kinetics of uracil formation in single and double-stranded DNA by deamination of cytosine in cyclobutane pyrimidine dimers.
Unusual kinetics of uracil formation in single and double-stranded DNA by deamination of cytosine in cyclobutane pyrimidine dimers.
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通过环丁烷嘧啶二聚体中胞嘧啶脱氨基作用在单链和双链 DNA 中形成尿嘧啶的异常动力学。
DOI：
10.1006/jmbi.1994.1040
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发表时间：
1994
影响因子：
5.6
通讯作者：
Liu,SK
中科院分区：
文献类型：
--
作者：
Tessman,I;Kennedy,MA;Liu,SK
诱变研究表明，紫外线诱导的环丁烷嘧啶二聚体中胞嘧啶的脱氨基作用是一个无错误过程的关键部分，可以解释大多数C→T碱基特异性，而C→T碱基特异性通常是紫外线诱导诱变的特征。从延迟光复活的致突变效应推断，脱氨动力学与阶跃函数的相似性是显著的。为了从不同的角度研究动力学，我们使用了结合光裂合酶和尿嘧啶-N-糖基化酶处理的酶促方法来检测噬菌体S13在UV照射的单链或双链感染性DNA中尿嘧啶的形成。通过去除尿嘧啶形成脱碱基位点推断感染性丧失。可以得出结论，在37°C下，在照射后20分钟（单链DNA）或40分钟（双链DNA）内没有尿嘧啶出现，但在这些潜伏期之后，大多数尿嘧啶残基在以照射后29分钟（单链DNA）和55分钟（双链DNA）为中心的短暂14分钟内迅速出现。时间似乎完全证实了先前的证据，即DNA中的二聚体胞嘧啶脱氨基与阶跃函数样动力学。此外，尿嘧啶的外观被证明是依赖于含有胞嘧啶的环丁烷二聚体的UV诱导。
Mutagenesis studies have indicated that the deamination of cytosine in UV-induced cyclobutane pyrimidine dimers is a key part of an error-free process that can account for most of the C→T base specificity that frequently characterizes UV-induced mutagenesis. The kinetics of deamination, as inferred from the mutagenic effect of delayed photoreactivation, is remarkable in its resemblance to a step function. To study the kinetics from a different point of view, we used an enzymatic approach combining photolyase and uracil-N-glycosylase treatment to detect the formation of uracil in UV-irradiated single or double-stranded infectious DNA of phage S13. Formation of abasic sites by removal of uracil was inferred from loss of infectivity. It is concluded that no uracil appeared at 37°C within 20 minutes (single-stranded DNA) or 40 minutes (double-stranded DNA) after irradiation, but following those latent periods, most of the uracil residues rapidly appeared within a brief 14 minute period centered at 29 minutes (single-stranded DNA) and 55 minutes (double-stranded DNA) after irradiation. The timing appears to fully confirm the previous evidence that dimer cytosines in DNA deaminate with step-function-like kinetics. Furthermore, the appearance of uracil was shown to be dependent on the UV-induction of cyclobutane dimers containing cytosine.