Environmental Science and Engineering, Qingdao University, Qingdao, 266071, China.
Marine Bioresources and Environment Research Center, First Institute of Oceanography, Ministry of Natural Resources, 6 XianXiaLing Road, Qingdao, Shandong, China.
Biotechnol Lett. 2021 Jul;43(7):1349-1355. doi: 10.1007/s10529-021-03107-z. Epub 2021 Mar 10.
All RecJ proteins are known to date only perform exonuclease activity. The present study reports that a novel RecJ protein obtained from Bacillus cereus isolated from marine sediments has both endonuclease and exonuclease activities.
Analysis of the BcRecJ expression induction in E. coli BL21 revealed that the BcRecJ protein cleaved plasmids and genomic DNA in the host cell, and led to cell death and decreased the DNA content. Further, the BcRecJ protein had the ability to degrade supercoiled plasmid DNA into circular or linear forms in vitro. Meanwhile, the BcRecJ protein loaded with an S-modified guide facilitated plasmid linearization and reduced smear formation.
The results suggested that this novel BcRecJ protein was different from any reported RecJs and had a longer C-terminus. Testing the BcRecJ mutants indicated that the endonuclease activity was affected by two residues of BcRecJ (D561, E637) after testing the BcRecJ mutants.
The discovery of the type of protein is a new breakthrough for the RecJ proteins, which has both endonuclease and exonuclease activities.
迄今为止，所有 RecJ 蛋白都被认为只具有核酸外切酶活性。本研究报告称，从海洋沉积物中分离出的一种新型芽孢杆菌 RecJ 蛋白具有内切酶和核酸外切酶活性。
在大肠杆菌 BL21 中分析 BcRecJ 的表达诱导，发现 BcRecJ 蛋白在宿主细胞中切割质粒和基因组 DNA，导致细胞死亡和 DNA 含量降低。此外，BcRecJ 蛋白在体外具有将超螺旋质粒 DNA 降解为环状或线性形式的能力。同时，负载 S 修饰向导的 BcRecJ 蛋白有助于质粒线性化并减少拖尾形成。
结果表明，这种新型 BcRecJ 蛋白与任何已报道的 RecJs 不同，其 C 端更长。测试 BcRecJ 突变体表明，内切酶活性受 BcRecJ 中的两个残基（D561、E637）影响。
该蛋白的发现是 RecJ 蛋白的一个新突破，它具有内切酶和核酸外切酶活性。
