Escherichia coli cells bearing mutA, a mutant glyV tRNA gene, express a recA-dependent error-prone DNA replication activity.
Escherichia coli cells bearing mutA, a mutant glyV tRNA gene, express a recA-dependent error-prone DNA replication activity.
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带有 mutA（一种突变的 glyV tRNA 基因）的大肠杆菌细胞表达依赖于 recA 的易错 DNA 复制活性。
DOI：
10.1046/j.1365-2958.1999.01520.x
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发表时间：
1999
影响因子：
3.6
通讯作者：
Humayun,MZ
中科院分区：
文献类型：
--
作者：
AlMamun,AA;Rahman,MS;Humayun,MZ
大肠杆菌glyVtRNA基因中的一个碱基替换突变（穆塔）增强了asp → gly的错误翻译，并赋予了一个强的突变子表型，该表型不依赖SOS，但需要recA、recBandrecC基因。 在这里，我们证明了mutA细胞表达一种易错的DNA聚合酶，通过使用一种体外实验系统，该系统基于将携带模型诱变损伤的噬菌体M13单链病毒DNA转化为双链复制形式。对新合成的链进行扩增，然后进行多重DNA序列分析，结果显示，当用正常细胞提取物复制DNA时，3，N4-乙烯基胞嘧啶（CXC）的突变固定率为1.3%，当用mutAcell提取物复制时为1.48%，当用mutA recAdouble突变细胞提取物复制时为1.3%，与先前的体内结果完全一致。在M13 lacZ（α）正向突变系统中，mutAcell无提取物显著提高了未损伤DNA位点的突变。NeitherpolA（DNA聚合酶I）和norpolB（DNA聚合酶II）基因是突变A表型所必需的，这表明突变A表型是通过DNA聚合酶III的修饰或先前未鉴定的DNA聚合酶的激活介导的。这些发现定义了一种新的诱变途径的主要特征，并暗示翻译，重组和复制之间存在以前未被认识到的联系。
A base substitution mutation (mutA) in theEscherichia coli glyVtRNA gene potentiates asp → gly mistranslation and confers a strong mutator phenotype that is SOS independent, but requiresrecA,recBandrecCgenes. Here, we demonstrate thatmutAcells express an error‐prone DNA polymerase by using anin vitroexperimental system based on the conversion of phage M13 single‐stranded viral DNA bearing a model mutagenic lesion to the double‐stranded replicative form. Amplification of the newly synthesized strand followed by multiplex DNA sequence analysis revealed that mutation fixation at 3,N4‐ethenocytosine (ɛC) was ≈3% when the DNA was replicated by normal cell extracts, ≈48% when replicated bymutAcell extracts and ≈3% when replicated bymutA recAdouble mutant cell extracts, in complete agreement with previousin vivoresults. Mutagenesis at undamaged DNA sites was significantly elevated bymutAcell‐free extracts in the M13lacZ(α) forward mutagenesis system. NeitherpolA(DNA polymerase I) norpolB(DNA polymerase II) genes are required for themutAphenotype, suggesting that the phenotype is mediated through a modification of DNA polymerase III or the activation of a previously unidentified DNA polymerase. These findings define the major features of a novel mutagenic pathway and imply the existence of previously unrecognized links between translation, recombination and replication.