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首页> 外文期刊>Journal of bacteriology >Short-Sequence Tandem and Nontandem DNA Repeats and Endogenous Hydrogen Peroxide Production Contribute to Genetic Instability of Streptococcus pneumoniae
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Short-Sequence Tandem and Nontandem DNA Repeats and Endogenous Hydrogen Peroxide Production Contribute to Genetic Instability of Streptococcus pneumoniae

机译：短序列串联和非串联DNA重复和内源性过氧化氢的产生有助于肺炎链球菌的遗传不稳定。

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Loss-of-function mutations in the following seven pneumococcal genes were detected and analyzed: pspA, spxB, xba, licD2, lytA, nanA, and atpC. Factors associated with these mutations included (i) frameshifts caused by reversible gain and loss of single bases within homopolymeric repeats as short as 6 bases, (ii) deletions caused by recombinational events between nontandem direct repeats as short as 8 bases, and (iii) substitutions of guanine residues caused at an increased frequency by the high levels of hydrogen peroxide (>2 mM) typically generated by this species under aerobic growth conditions. The latter accounted for a frequency as high as 2.8 × 10?6 for spontaneous mutation to resistance to optochin and was 10- to 200-fold lower in the absence of detectable levels of H2O2. Some of these mutations appear to have been selected for in vivo during pneumococcal infection, perhaps as a consequence of immune pressure or oxidative stress.
机译：检测并分析了以下七个肺炎球菌基因的功能丧失突变： pspA ， spxB ， xba ， licD2 ， lytA ， nanA 和 atpC 。与这些突变相关的因素包括：（i）由短至6个碱基的均聚物重复序列中单碱基的可逆获得和丢失引起的移码;（ii）由短至8个碱基的非串联直接重复之间的重组事件引起的缺失;以及（iii）在好氧生长条件下，该物种通常产生的高水平过氧化氢（> 2 mM）导致鸟嘌呤残基的取代频率增加。后者占自发对视蛋白抵抗力突变的频率高达2.8×10 ？6 ，在没有可检测水平的H 2 <的情况下，后者的频率降低了10-200倍。 / sub> O 2 。这些突变中的某些似乎是在肺炎球菌感染期间选择用于体内的，可能是由于免疫压力或氧化应激的结果。

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