Ishino Sonoko, Nishi Yuki, Oda Soichiro, Uemori Takashi, Sagara Takehiro, Takatsu Nariaki, Yamagami Takeshi, Shirai Tsuyoshi, Ishino Yoshizumi
Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, Fukuoka 812-8581, Japan
Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, Fukuoka 812-8581, Japan.
Nucleic Acids Res. 2016 Apr 20;44(7):2977-86. doi: 10.1093/nar/gkw153. Epub 2016 Mar 21.
The common mismatch repair system processed by MutS and MutL and their homologs was identified in Bacteria and Eukarya. However, no evidence of a functional MutS/L homolog has been reported for archaeal organisms, and it is not known whether the mismatch repair system is conserved in Archaea. Here, we describe an endonuclease that cleaves double-stranded DNA containing a mismatched base pair, from the hyperthermophilic archaeon Pyrococcus furiosus The corresponding gene revealed that the activity originates from PF0012, and we named this enzyme Endonuclease MS (EndoMS) as the mismatch-specific Endonuclease. The sequence similarity suggested that EndoMS is the ortholog of NucS isolated from Pyrococcus abyssi, published previously. Biochemical characterizations of the EndoMS homolog from Thermococcus kodakarensis clearly showed that EndoMS specifically cleaves both strands of double-stranded DNA into 5'-protruding forms, with the mismatched base pair in the central position. EndoMS cleaves G/T, G/G, T/T, T/C and A/G mismatches, with a more preference for G/T, G/G and T/T, but has very little or no effect on C/C, A/C and A/A mismatches. The discovery of this endonuclease suggests the existence of a novel mismatch repair process, initiated by the double-strand break generated by the EndoMS endonuclease, in Archaea and some Bacteria.
由MutS和MutL及其同源物处理的常见错配修复系统在细菌和真核生物中被发现。然而，尚未有关于古生菌中功能性MutS/L同源物的报道，并且也不清楚错配修复系统在古生菌中是否保守。在此，我们描述了一种来自嗜热古菌激烈火球菌的内切核酸酶，它能切割含有错配碱基对的双链DNA。相应的基因表明该活性源自PF0012，我们将这种酶命名为内切核酸酶MS（EndoMS），作为错配特异性内切核酸酶。序列相似性表明EndoMS是先前发表的从深渊火球菌中分离出的NucS的直系同源物。来自柯达氏嗜热栖热菌的EndoMS同源物的生化特性清楚地表明，EndoMS能将双链DNA的两条链特异性切割成5'突出端形式，错配碱基对位于中心位置。EndoMS能切割G/T、G/G、T/T、T/C和A/G错配，对G/T、G/G和T/T的偏好性更高，但对C/C、A/C和A/A错配几乎没有影响或没有影响。这种内切核酸酶的发现表明，在古生菌和一些细菌中存在一种由EndoMS内切核酸酶产生的双链断裂引发的新型错配修复过程。
