Structures of RecBCD in complex with phage-encoded inhibitor proteins reveal distinctive strategies for evasion of a bacterial immunity hub.
Structures of RecBCD in complex with phage-encoded inhibitor proteins reveal distinctive strategies for evasion of a bacterial immunity hub.
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DOI：
10.7554/elife.83409
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发表时间：
2022-12-19
期刊：
影响因子：
7.7
通讯作者：
Dillingham MS
中科院分区：
文献类型：
--
作者：
Wilkinson M;Wilkinson OJ;Feyerherm C;Fletcher EE;Wigley DB;Dillingham MS
在感染细菌细胞后，噬菌体调节双链DNA断裂修复途径，以保护自己免受宿主免疫系统的攻击，并优先考虑自己的重组酶。本文对靶向DNA断裂切除复合体RecBCD的两种噬菌体蛋白gp5.9和Abc2进行了生化和结构分析。这些例子说明了控制DNA断裂修复的两种截然不同的机制，其中RecBCD复合体要么被抑制，要么被吸收，以使入侵的噬菌体受益。Gp5.9通过阻止其与DNA结合来完全抑制RecBCD。RecBCD-gp5.9的结构表明，gp5.9通过底物模拟作用，主要结合到RecB臂结构域，并在空间上竞争DNA结合位点。Gp5.9采用了一种平行的螺旋结构，这对于天然DNA模拟蛋白来说是前所未有的。相比之下，Abc2的结合对分离的RecBCD的生化活性没有实质性的影响。RecBCD-Abc2结构表明，Abc2结合到RecC亚基的chi -识别结构域的位置可能使其能够介导噬菌体重组酶装载到其单链DNA产物上。
Following infection of bacterial cells, bacteriophage modulate double-stranded DNA break repair pathways to protect themselves from host immunity systems and prioritise their own recombinases. Here, we present biochemical and structural analysis of two phage proteins, gp5.9 and Abc2, which target the DNA break resection complex RecBCD. These exemplify two contrasting mechanisms for control of DNA break repair in which the RecBCD complex is either inhibited or co-opted for the benefit of the invading phage. Gp5.9 completely inhibits RecBCD by preventing it from binding to DNA. The RecBCD-gp5.9 structure shows that gp5.9 acts by substrate mimicry, binding predominantly to the RecB arm domain and competing sterically for the DNA binding site. Gp5.9 adopts a parallel coiled-coil architecture that is unprecedented for a natural DNA mimic protein. In contrast, binding of Abc2 does not substantially affect the biochemical activities of isolated RecBCD. The RecBCD-Abc2 structure shows that Abc2 binds to the Chi-recognition domains of the RecC subunit in a position that might enable it to mediate the loading of phage recombinases onto its single-stranded DNA products.