Yeh Fu-Lung, Wang Shi-Ya, Hsu Lung-Ying, Wang Dar-Yi, Hsu Todd
Institute of Bioscience and Biotechnology, National Taiwan Ocean University, Keelung 20224, Taiwan, Republic of China.
Biochim Biophys Acta. 2004 Oct 21;1680(2):129-36. doi: 10.1016/j.bbaexp.2004.08.005.
Eukaryotic mismatch repair of simple base mispairs and small insertion-deletion loops is activated by the binding of a heterodimeric complex composed of MutS homolog 2(MSH2) and MSH6. Here we report the cloning of zebrafish (Danio rerio) MSH2 (zMSH2) cDNA that has an open reading frame of 2811 nucleotides encoding a polypeptide of 936 amino acids. The deduced amino acid sequence of zMSH2 shares a 69% identity to both human and mouse MSH2. The zMSH2 protein contains a putative tyrosine-42 mismatch-contacting residue located at the N-terminal mismatch recognition region and four C-terminal ATP-binding consensus sequences conserved among MutS homologs. The 105-kDa recombinant zMSH2 bound apparently stronger to a G-T heteroduplex than to a homoduplex probe as shown by a gel shift assay. A preferential expression of both zMSH2 and zMSH6 mRNA in early embryos was found by Northern blot analysis. Whole mount in situ hybridization revealed a major expression of zMSH2 in different regions of the brain, including eyes, telencephalon, and the fourth ventricle in 12- to 48-h-old embryos. The production of zMSH2 mRNA gradually decreased in more mature 60- to 120-h-old zebrafish, reflecting a positive correlation between the amount of proliferating cells and MSH gene expression.
由MutS同源物2（MSH2）和MSH6组成的异二聚体复合物的结合可激活真核生物对简单碱基错配和小插入-缺失环的错配修复。在此，我们报告了斑马鱼（Danio rerio）MSH2（zMSH2）cDNA的克隆，其开放阅读框为2811个核苷酸，编码一个936个氨基酸的多肽。推导的zMSH2氨基酸序列与人和小鼠的MSH2均具有69%的同一性。zMSH2蛋白在N端错配识别区域含有一个推定的与错配接触的酪氨酸-42残基，以及四个在MutS同源物中保守的C端ATP结合共有序列。凝胶迁移试验表明，105-kDa的重组zMSH2与G-T异源双链体的结合明显强于与同源双链体探针的结合。Northern印迹分析发现zMSH2和zMSH6 mRNA在早期胚胎中均有优先表达。整体原位杂交显示，在12至48小时龄的胚胎中，zMSH2在大脑的不同区域有主要表达，包括眼睛、端脑和第四脑室。在更成熟的60至120小时龄斑马鱼中，zMSH2 mRNA的产生逐渐减少，这反映了增殖细胞数量与MSH基因表达之间的正相关。
