PREFERENTIAL DNA SECONDARY STRUCTURE MUTAGENESIS IN THE LAGGING STRAND OF REPLICATION IN ESCHERICHIA-COLI
PREFERENTIAL DNA SECONDARY STRUCTURE MUTAGENESIS IN THE LAGGING STRAND OF REPLICATION IN ESCHERICHIA-COLI
复制标题
DOI：
10.1038/352544a0
复制
发表时间：
1991-08-08
期刊：
影响因子：
64.8
通讯作者：
SINDEN, RR
中科院分区：
文献类型：
--
作者：
TRINH, TQ;SINDEN, RR
当存在于单链DNA中时，回文或准回文序列具有形成复杂二级结构的潜力，包括发夹，其可促进同向重复的链间错配，并负责不同类型的基于复制的突变，包括缺失、添加、移码和重复1-5。 在回文对称的区域中，特定的缺失事件可能涉及发夹或其他DNA二级结构的形成，其可以稳定同向重复序列1，2的未对准。 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。 并行DNA复制模型，涉及不对称二聚体DNA聚合酶III复合物，其复制前导链和滞后链8，对诱变具有重要意义。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'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 quasipalindromic sequences have the potential to form complex secondary structures, including hairpins, which may facilitate interstrand misalignment of direct repeats and be responsible for diverse types of replication-based mutations, including deletions, additions, frameshifts and duplications 1-5. 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 repeats 1,2. One model suggests that these deletions occur during DNA replication by slippage of the template strand and misalignment with the progeny strand 6,7. The concurrent DNA replication model, involving an asymmetric dimeric DNA polymerase III complex which replicates the leading and lagging strands 8, 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 chloramphenicol 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.