College of Environmental Science and Engineering, Qingdao University, Qingdao, 266071, China.
Marine Bioresources and Environment Research Center, First Institute of Oceanography, Ministry of Natural Resources, Qingdao, 266061, China.
FEBS Lett. 2020 Jul;594(14):2303-2310. doi: 10.1002/1873-3468.13809. Epub 2020 Jun 15.
RecJ homologs, which occur in virtually all prokaryotes and eukaryotes, play key roles in DNA damage repair and recombination. Current evidence shows that RecJ family proteins exhibit exonuclease activity, degrading single-stranded nucleic acids. Here, we report a novel RecJ isolated from Bacillus halodurans, which utilizes double-stranded DNA as a substrate and functions as an endonuclease. Bacillus halodurans RecJ (BhRecJ) cleaves supercoiled plasmids into open circular and linear forms. Besides the typical domains of DHH, DHHA1, and oligonucleotide-binding-fold, BhRecJ possesses a C-terminal domain with unknown function, which might form the core of the endonuclease activity. Using mutational analysis, we mapped several essential residues for BhRecJ endonuclease activity. Our findings suggest that BhRecJ may be involved in biological processes not typically associated with RecJ proteins.
RecJ 同源物几乎存在于所有原核生物和真核生物中，在 DNA 损伤修复和重组中发挥关键作用。目前的证据表明，RecJ 家族蛋白具有核酸外切酶活性，可降解单链核酸。本文报道了一种从嗜盐杆菌中分离出的新型 RecJ，它以双链 DNA 为底物，作为一种内切核酸酶发挥作用。嗜盐杆菌 RecJ（BhRecJ）可将超螺旋质粒切割成开环和线性形式。除了 DHH、DHHA1 和寡核苷酸结合结构域的典型结构域外，BhRecJ 还具有一个具有未知功能的 C 末端结构域，该结构域可能形成内切核酸酶活性的核心。通过突变分析，我们定位了几个对 BhRecJ 内切核酸酶活性至关重要的残基。我们的研究结果表明，BhRecJ 可能参与了与 RecJ 蛋白通常不相关的生物学过程。
