Structural basis of the 3'-end recognition of a leading strand in stalled replication forks by PriA
Structural basis of the 3'-end recognition of a leading strand in stalled replication forks by PriA
复制标题
DOI：
10.1038/sj.emboj.7601697
复制
发表时间：
2007-05-16
期刊：
影响因子：
11.4
通讯作者：
Kohda, Daisuke
中科院分区：
文献类型：
--
作者：
Sasaki, Kaori;Ose, Toyoyuki;Kohda, Daisuke
在真细菌中，PriA 解旋酶检测停滞的 DNA 复制叉。 PriA 的这一关键作用归因于它能够与停滞的复制叉中新生引导 DNA 链的 3' 端结合。寡核苷酸复合物的晶体结构以及荧光相关光谱和诱变的结合表明，PriA 的 N 端结构域具有 DNA 3' 端核苷酸残基的结合口袋。与脱氧核糖 3'-OH 的相互作用对于 3' 末端识别至关重要。相反，考虑到与 3' 末端携带四个碱基的寡核苷酸具有相同的亲和力，与 3' 末端核碱基的直接相互作用是出乎意料的。因此，除了脱氧核糖和 5' 侧磷酸二酯基团之外，PriA 的 N 端结构域还以碱基非选择性方式识别 3'' 端核苷酸的 3' 端碱基，以获得足够的亲和力和非选择性，以发现 DNA 复制过程中产生的所有停滞的复制叉。这一独特的特征是 PriA 解旋酶结构域在未复制的双链 DNA 上正确定位的先决条件。
In eubacteria, PriA helicase detects the stalled DNA replication forks. This critical role of PriA is ascribed to its ability to bind to the 3' end of a nascent leading DNA strand in the stalled replication forks. The crystal structures in complexes with oligonucleotides and the combination of fluorescence correlation spectroscopy and mutagenesis reveal that the N-terminal domain of PriA possesses a binding pocket for the 3'-terminal nucleotide residue of DNA. The interaction with the deoxyribose 3'-OH is essential for the 3'-terminal recognition. In contrast, the direct interaction with 3'-end nucleobase is unexpected, considering the same affinity for oligonucleotides carrying the four bases at the 3' end. Thus, the N-terminal domain of PriA recognizes the 3'end base in a base-non-selective manner, in addition to the deoxyribose and 5'-side phosphodiester group, of the 3''-terminal nucleotide to acquire both sufficient affinity and non-selectivity to find all of the stalled replication forks generated during DNA duplication. This unique feature is prerequisite for the proper positioning of the helicase domain of PriA on the unreplicated double-stranded DNA.