Preferential DNA secondary structure mutagenesis in the lagging strand of replication in E. coli
Preferential DNA secondary structure mutagenesis in the lagging strand of replication in E. coli
复制标题
大肠杆菌复制滞后链中的优先 DNA 二级结构诱变
作者：
T. Q. Trinh;R. Sinden
当存在于单链DNA中时，回文或准回文序列有可能形成复杂的二级结构，包括发夹，这可能促进同向重复序列的链间错配，并导致不同类型的基于复制的突变，包括缺失、添加、移码和复制1 -5。在回文对称区域，特定的缺失事件可能涉及发夹或其他DNA二级结构的形成，这些结构可以稳定直接重复的未对齐1，2。一个模型表明，这些缺失发生在DNA复制过程中，通过模板链的滑动和与子代链的错位6，7。同时DNA复制模型，涉及一个不对称的二聚体DNA聚合酶III复合物，复制的领先和落后strands 8，诱变有显着的影响。滞后链模板的间歇性成环，以及滞后链模板可能包含冈崎片段长度的单链DNA区域的事实，为DNA二级结构形成和错位提供了机会。在这里，我们报告我们的设计回文片段创建一个'不对称回文插入'的氯霉素乙酰转移酶基因质粒pBR 325。插入片段在大肠杆菌中缺失的频率取决于基因在质粒中的方向。我们的研究结果表明，复制依赖性缺失之间的直接重复序列可能会优先发生在滞后链。
WHEN present in single-stranded DNA, palindromic or quasi-palindromic sequences have the potential to form complex secondary structures, including hairpins, which may facilitate inter-strand misalignment of direct repeats and be responsible for diverse types of replication-based mutations, including deletions, additions, frameshifts and duplications1–5. In regions of palindromic symmetry, specific deletion events may involve the formation of a hairpin or other DNA secondary structures which can stabilize the misalignment of direct repeats1,2. One model suggests that these deletions occur during DNA replication by slippage of the template strand and misalignment with the progeny strand6,7. The concurrent DNA replication model, involving an asymmetric dimeric DNA polymerase III complex which replicates the leading and lagging strands8, has significant implications for mutagenesis. The intermittent looping of the lagging strand template, and the fact that the lagging strand template may contain a region of single-stranded DNA the length of an Okazaki fragment, provides an opportunity for DNA secondary-structure formation and misalignment. Here we report our design of a palindromic fragment to create an 'asymmetric palindromic insert' in the chloram-phenicol acetyltransferase gene of plasmid pBR325. The frequency with which the insert was deleted in Escherichia coli depends on the orientation of the gene in the plasmid. Our results suggest that replication-dependent deletion between direct repeats may occur preferentially in the lagging strand.
回文和非回文序列在体外和体内阻止 DNA 合成中的作用。
影响因子：
5.6
作者：
Weaver,DT;DePamphilis,ML
通讯作者：
DePamphilis,ML