G-quadruplex forming structural motifs in the genome of Deinococcus radiodurans and their regulatory roles in promoter functions
G-quadruplex forming structural motifs in the genome of Deinococcus radiodurans and their regulatory roles in promoter functions
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DOI：
10.1007/s00253-015-6808-6
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发表时间：
2015-11-01
影响因子：
5
通讯作者：
Misra, Hari S.
中科院分区：
文献类型：
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作者：
Kota, Swathi;Dhamodharan, V.;Misra, Hari S.
在鸟嘌呤四链体（G4）结合药物（G4药物）存在下，耐辐射异常球菌显示出受损的辐射抗性。全基因组扫描显示，在编码序列的上游区域以及许多基因的结构区域中存在鸟嘌呤序列（G基序），表明G4 DNA在该细菌基因组功能的调节中发挥作用。合成了存在于一些DNA损伤响应基因如莱克萨、pprI、recF、recQ、mutL和radA上游的G基序，并在体外探测了G4 DNA结构的形成。位于recQ上游第67位和mutL上游第121位的G基序分别产生平行和混合的G4 DNA结构。在正常生长条件下，含有各自G基序的recQ和mutL启动子下的β-半乳糖苷酶表达被G4药物抑制。耐辐射的然而，当这样的细胞暴露于γ辐射时，mutL启动子活性被刺激，而recQ启动子活性在G4药物的存在下被抑制。从recQ启动子中删除G基序可以使其免于G4药物抑制。D.用G4药物处理的耐辐射细菌细胞显示recQ表达和γ辐射抗性的降低，表明G4 DNA参与该细菌的辐射抗性。这些结果表明，D.至少在体外，耐辐射菌基因组形成不同类型的G4 DNA结构，并且recQ和mutL启动子似乎在G4 DNA结构水平上受到差异调节。
Deinococcus radiodurans displays compromised radioresistance in the presence of guanine quadruplex (G4)-binding drugs (G4 drugs). Genome-wide scanning showed islands of guanine runs (G-motif) in the upstream regions of coding sequences as well as in the structural regions of many genes, indicating a role for G4 DNA in the regulation of genome functions in this bacterium. G-motifs present upstream to some of the DNA damage-responsive genes like lexA, pprI, recF, recQ, mutL and radA were synthesized, and the formation of G4 DNA structures was probed in vitro. The G-motifs present at the 67th position upstream to recQ and at the 121st position upstream to mutL produced parallel and mixed G4 DNA structures, respectively. Expression of beta-galactosidase under recQ and mutL promoters containing respective G-motifs was inhibited by G4 drugs under normal growth conditions in D. radiodurans. However, when such cells were exposed to gamma radiation, mutL promoter activity was stimulated while recQ promoter activity was inhibited in the presence of G4 drugs. Deletion of the G-motif from the recQ promoter could relax it from G4 drug repression. D. radiodurans cells treated with G4 drug showed reduction in recQ expression and gamma radiation resistance, indicating an involvement of G4 DNA in the radioresistance of this bacterium. These results suggest that G-motifs from D. radiodurans genome form different types of G4 DNA structures at least in vitro, and the recQ and mutL promoters seem to be differentially regulated at the levels of G4 DNA structures.