Zhou Hanying, Li Pengpeng, Wu Dongxia, Ran Tingting, Wang Weiwu, Xu Dongqing
Key Laboratory of Microbiological Engineering of Agricultural Environment of Ministry of Agriculture, Department of Microbiology, College of Life Sciences, Nanjing Agricultural University, Nanjing, China, 210095.
Key Laboratory of Microbiological Engineering of Agricultural Environment of Ministry of Agriculture, Department of Microbiology, College of Life Sciences, Nanjing Agricultural University, Nanjing, China, 210095
FEMS Microbiol Lett. 2015 Dec;362(24):fnv204. doi: 10.1093/femsle/fnv204. Epub 2015 Oct 22.
The HNH endonuclease superfamily usually contains a conserved HNH motif in the sequence, and the second subfamily of it uses N to replace the second H in the HNH motif. A bacterium with extracellular thermostable DNase was isolated and identified as Exiguobacterium sp. yc3. A 20 kDa putative DNase was later purified and the encoding gene of it was amplified and sequenced, the deduced amino acid sequence analysis showed that the protein belongs to the HNH endonuclease superfamily, and therefore it was named as EheA ( E: xiguobacterium H: NH E: ndonuclease). Characterization of the recombinant EheA confirmed that EheA is a DNase. By site-directed mutation method, H116, N141 and N156 were proved to be essential for the DNase activity. EheA is the first experimentally determined bacterial source endonuclease belonging to the second subfamily of HNH superfamily. Further bioinformatic analysis showed that EheA homologue genes are conserved in the Exiguobacterium species, which suggests their possible important functions for Exiguobacterium species. And as a thermostable DNase, EheA also has a promising future in many application fields.
HNH核酸内切酶超家族通常在序列中含有一个保守的HNH基序，其第二个亚家族在HNH基序中用N取代了第二个H。分离出一株具有胞外耐热DNA酶的细菌，并鉴定为嗜麦芽窄食单胞菌yc3。随后纯化了一种假定的20 kDa DNA酶，并对其编码基因进行了扩增和测序，推导的氨基酸序列分析表明该蛋白属于HNH核酸内切酶超家族，因此将其命名为EheA（E：嗜麦芽窄食单胞菌，H：HNH，E：核酸内切酶）。重组EheA的特性鉴定证实EheA是一种DNA酶。通过定点突变方法，证明H116、N141和N156对DNA酶活性至关重要。EheA是第一个通过实验确定的属于HNH超家族第二个亚家族的细菌来源核酸内切酶。进一步的生物信息学分析表明，EheA同源基因在嗜麦芽窄食单胞菌物种中是保守的，这表明它们对嗜麦芽窄食单胞菌物种可能具有重要功能。并且作为一种耐热DNA酶，EheA在许多应用领域也具有广阔的前景。
