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首页> 外文期刊>Infection and immunity >Phenotypes of a Naturally Defective recB Allele in Neisseria meningitidis Clinical Isolates
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Phenotypes of a Naturally Defective recB Allele in Neisseria meningitidis Clinical Isolates

机译：脑膜炎奈瑟氏球菌临床分离株中自然缺陷recB等位基因的表型。

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Neisseria meningitidis strains belonging to the hypervirulent lineage ET-37 and several unrelated strains are extremely UV sensitive. The phenotype is consequent to the presence of a nonfunctional recBET-37 allele carrying multiple missense mutations. Phenotypic analysis has been performed with congenic meningococcal strains harboring either the wild-type recB allele or the recBET-37 allele. Congenic recBET-37 meningococci, in addition to being sensitive to UV, were defective both in repair of DNA lesions induced by UV treatment and, partially, in recombination-mediated transformation. Consistently, the wild-type, but not the recBET-37, allele was able to complement the Escherichia coli recB21 mutation to UV resistance and proficiency in recombination. recBET-37 meningococci did not exhibit higher frequencies of spontaneous mutation to rifampin resistance than recB-proficient strains. However, mutation rates were enhanced following UV treatment, a phenomenon not observed in the recB-proficient counterpart. Interestingly, the results of PCR-based assays demonstrated that the presence of the recBET-37 allele considerably increased the frequency of recombination at the pilin loci. The main conclusion that can be drawn is that the presence of the defective recBET-37 allele in N. meningitidis isolates causes an increase in genetic diversity, due to an ineffective RecBCD-dependent DNA repair and recombination pathway, and an increase in pilin antigenic variation.
机译：属于高毒谱系ET-37的脑膜炎奈瑟氏球菌菌株和一些无关的菌株对紫外线极为敏感。该表型是由于存在携带多个错义突变的非功能性 recB ET-37 等位基因而导致的。已经对带有野生型 recB 等位基因或 recB ET-37 等位基因的同基因脑膜炎球菌菌株进行了表型分析。同基因的 recB ET-37 脑膜炎球菌除了对紫外线敏感外，在紫外线处理诱导的DNA损伤修复中以及重组介导的转化中均存在缺陷。一致地，野生型而不是 recB ET-37 等位基因能够补充大肠杆菌recB21 突变对紫外线的抵抗力和精通重组。 recB ET-37 脑膜炎球菌与利福平耐药菌株相比，对利福平耐药的自发突变频率更高。但是，紫外线处理后突变率提高了，这是 recB 精通技术中未发现的现象。有趣的是，基于PCR的检测结果表明 recB ET-37 等位基因的存在大大增加了菌毛基因座处的重组频率。可以得出的主要结论是在 N中存在缺陷的 recB ET-37 等位基因。由于无效的依赖RecBCD的DNA修复和重组途径以及脑毛蛋白抗原变异的增加，脑膜炎双球菌分离株导致遗传多样性增加。

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