Polymerase-specific differences in the DNA intermediates of frameshift mutagenesis. In vitro synthesis errors of Escherichia coli DNA polymerase I and its large fragment derivative.
Polymerase-specific differences in the DNA intermediates of frameshift mutagenesis. In vitro synthesis errors of Escherichia coli DNA polymerase I and its large fragment derivative.
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移码诱变 DNA 中间体的聚合酶特异性差异。
DOI：
10.1016/0022-2836(89)90258-1
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发表时间：
1989
影响因子：
5.6
通讯作者：
Ripley,LS
中科院分区：
文献类型：
--
作者：
Papanicolaou,C;Ripley,LS
比较了600多个移码突变的序列，这些移码突变是由大肠杆菌聚合酶I酶（PolI）或其大片段衍生物（PolLF）在体外以阿托伐他汀引发的单链DNA模板进行DNA复制的结果。发现了四种类型的突变体：（1）单碱基缺失，（2）碱基取代，（3）多碱基缺失和（4）复杂的移码突变，在一个协调的突变过程中改变碱基序列和碱基数量。模板序列5′-Py-T-G-3′，先前被鉴定为G对面单碱基缺失的PolLF热点，也是PolI的热点。鉴定了单碱基缺失的PolI特异性暖点。在碱基替换中，转换比颠换更频繁。颠换由（模板）G · G、（模板）G · A和（模板）C · T错配对介导。多个碱基缺失仅在PolI复制后发现。虽然这些缺失中的每一个都可以通过直接重复的DNA序列介导的错位来解释，但相同长度的重复序列的缺失频率通常不同。PolI和PolLF都产生了许多复杂的移码突变体。突变位点的新序列与新合成的DNA链中附近的DNA序列完全互补。在每种情况下，回文互补性都可以介导启动突变过程所需的错位。错配的DNA合成解释了突变位点处的核苷酸变化和可以指导DNA在模板上重新排列的同源性。大多数复杂的突变体序列可以通过涉及新合成的DNA中的折回结构的分子内错配或通过链置换合成期间的链切换来启动。PolI和PolLF的复杂移码突变和多碱基缺失的特异性之间的显着差异确定了聚合酶特异性决定因素的存在，这些决定因素影响错配介导的移码和缺失的频率和特异性。
The sequences of more than 600 frameshift mutations produced as a consequence ofin vitroDNA replication on an oligonucleotide-primed, single-stranded DNA template by theEscherichia colipolymerase I enzyme (PolI) or its large fragment derivative (PolLF) were compared. Four categories of mutants were found: (1) single-base deletions, (2) base substitutions, (3) multiple-base deletions and (4) complex frameshift mutations that change both the base sequence and the number of bases in a concerted mutational process. The template sequence 5′-Py-T-G-3′, previously identified as a PolLF hotspot for single-base deletions opposite G, is also a hotspot for PolI. A PolI-specific warm spot for single-base deletions was identified. Among base substitutions, transitions were more frequent than transversions. Transversions were mediated by (template)G · G, (template)G · A, and (template)C · T mispairs. Multiple-base deletions were found only after PolI replication. Although each of these deletions can be explained by a misalignment mediated by directly repeated DNA sequences, deletion frequencies were often different for repeats of the same length. Both PolI and PolLF produced many complex frameshift mutants. The new sequences at the mutant sites are exactly complementary to nearby DNA sequences in the newly synthesized DNA strand. In each case, palindromic complementarity could mediate the misalignment needed to initiate the mutational process. The misaligned DNA synthesis accounts for the nucleotide changes at the mutant site and for homology that could direct realignment of the DNA onto the template. Most of the complex mutant sequences could be initiated by either intramolecular misalignments involving fold-back structures in newly synthesized DNA or by strand-switching during strand-displacement synthesis. The striking differences between the specificities of complex frameshift mutations and multiple-base deletions by PolI and PolLF identify the existence of polymerase-specific determinants that influence the frequency and specificity of misalignment-mediated frameshifts and deletions.