A Novel C-Terminal Domain of RecJ is Critical for Interaction with HerA in Deinococcus radiodurans.
A Novel C-Terminal Domain of RecJ is Critical for Interaction with HerA in Deinococcus radiodurans.
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RecJ 的新型 C 端结构域对于耐辐射球菌中与 HerA 的相互作用至关重要。
DOI：
10.3389/fmicb.2015.01302
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发表时间：
2015
影响因子：
5.2
通讯作者：
Hua Y
中科院分区：
文献类型：
--
作者：
Cheng K;Zhao Y;Chen X;Li T;Wang L;Xu H;Tian B;Hua Y
同源重组(HR)产生无错误的修复产物，在双链断裂修复和复制叉救过程中发挥重要作用。DNA末端切除是HR的关键步骤，通常由一系列核酸酶/解旋酶完成。RECJ被鉴定为参与细菌DNA末端切除的5‘-3’外切酶。典型的RecJ具有保守的DHH结构域、DHHA1结构域和寡核苷酸/寡糖结合(OB)折叠。然而，来自嗜热球菌门的RecJ，如耐辐射球菌RecJ(DrRecJ)，具有一个额外的C-末端结构域(CTD)，其功能尚未确定。在这里，我们发现，缺失CTD的drRecJ(drRecJΔC)不能恢复drrecJ突变株的生长和对丝裂霉素C(MMC)敏感的表型，这表明该结构域在体内对drRecJ是必不可少的。ΔC的DNA核酸酶活性和DNA结合能力均降低。DrRecJ-CTD和DrHerA之间存在直接相互作用，通过增强其DNA结合亲和力来刺激DrRecJ核酸酶的活性。此外，DrHerA的另一个伴侣DrNurA核酸酶通过与DrHerA相互作用，抑制了DrHerA对DrRecJ核酸酶活性的刺激。在recJ和Nura突变体之间观察到了相反的生长和MMC抗性表型。还提出了DrRecJ、DrHerA和DrNurA之间的一种新的调控机制。
Homologous recombination (HR) generates error-free repair products, which plays an important role in double strand break repair and replication fork rescue processes. DNA end resection, the critical step in HR, is usually performed by a series of nuclease/helicase. RecJ was identified as a 5′-3′ exonuclease involved in bacterial DNA end resection. Typical RecJ possesses a conserved DHH domain, a DHHA1 domain, and an oligonucleotide/oligosaccharide-binding (OB) fold. However, RecJs from Deinococcus-Thermus phylum, such as Deinococcus radiodurans RecJ (DrRecJ), possess an extra C-terminal domain (CTD), of which the function has not been characterized. Here, we showed that a CTD-deletion of DrRecJ (DrRecJΔC) could not restore drrecJ mutant growth and mitomycin C (MMC)-sensitive phenotypes, indicating that this domain is essential for DrRecJ in vivo. DrRecJΔC displayed reduced DNA nuclease activity and DNA binding ability. Direct interaction was identified between DrRecJ-CTD and DrHerA, which stimulates DrRecJ nuclease activity by enhancing its DNA binding affinity. Moreover, DrNurA nuclease, another partner of DrHerA, inhibited the stimulation of DrHerA on DrRecJ nuclease activity by interaction with DrHerA. Opposing growth and MMC-resistance phenotypes between the recJ and nurA mutants were observed. A novel modulation mechanism among DrRecJ, DrHerA, and DrNurA was also suggested.