Xu Chun-Yan, Yu Feng, Xu Si-Jie, Ding Yu, Sun Li-Hua, Tang Lin, Hu Xiao-Jian, Zhang Zhi-Hong, He Jian-Hua
Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China.
Biochim Biophys Acta. 2009 Jan;1794(1):118-23. doi: 10.1016/j.bbapap.2008.09.008. Epub 2008 Oct 1.
Sau3AI is a type II restriction enzyme that recognizes the 5'-GATC-3' sequence in double-strand DNA and cleaves at 5' to the G residue. The C-terminal domain of Sau3AI (Sau3AI-C), which contains amino acids from 233 to 489, was crystallized and its structure was solved by using the Multi-wavelength Anomalous Diffraction method. The Sau3AI-C structure at 1.9 A resolution is similar to the structure of MutH, a DNA mismatch repair protein that shares high sequence similarity with the N-terminal Sau3AI domain. The functional analysis shows that Sau3AI-C can bind DNA with one recognition sequence but has no cleavage activity. These results indicate that Sau3AI is a pseudo-dimer belonging to the type IIe restriction enzymes and the Sau3AI-C is the allosteric effector domain that assists DNA binding and cleavage.
Sau3AI是一种II型限制性内切酶，它识别双链DNA中的5'-GATC-3'序列，并在G残基的5'端进行切割。Sau3AI的C端结构域（Sau3AI-C）包含233至489位氨基酸，已结晶，并使用多波长反常衍射方法解析了其结构。分辨率为1.9 Å的Sau3AI-C结构与MutH的结构相似，MutH是一种DNA错配修复蛋白，与Sau3AI的N端结构域具有高度的序列相似性。功能分析表明，Sau3AI-C可以与一个识别序列结合DNA，但没有切割活性。这些结果表明，Sau3AI是属于IIe型限制性内切酶的假二聚体，而Sau3AI-C是协助DNA结合和切割的变构效应结构域。
