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首页> 外文期刊>Journal of bacteriology >Lysis of Escherichia coli by the bacteriophage phi X174 E protein: inhibition of lysis by heat shock proteins.
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Lysis of Escherichia coli by the bacteriophage phi X174 E protein: inhibition of lysis by heat shock proteins.

机译：噬菌体phi X174 E蛋白对大肠杆菌的裂解：通过热激蛋白抑制裂解。

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Lysis of Escherichia coli by the cloned E protein of bacteriophage phi X174 was more rapid than expected when bacteria were shifted from 30 to 42 degrees C at the time of E induction. Since such treatment also induces the heat shock response, we investigated the effect of heat shock proteins on lysis. An rpoH mutant was more sensitive to lysis by E, but a secondary suppressor mutation restored lysis resistance to parental levels, which suggests that the sigma 32 subunit itself did not directly increase lysis resistance. At 30 degrees C, mutants in five heat shock genes (dnaK, dnaJ, groEL, groES, and grpE) were more sensitive to lysis than were their wild-type parents. The magnitude of lysis sensitivity varied with mutation and strain background, with dnaK, dnaJ, and groES mutants consistently exhibiting the greatest sensitivities. Extended protection against lysis occurred when overproduction of heat shock proteins was induced artificially in cells that contained a plasmid with the rpoH+ gene under control of the tac promoter. This protective effect was completely abolished by mutations in dnaK, dnaJ, or groES but not by grpE or groEL mutations. Altered membrane behavior probably explains the contradiction whereby an actual temperature shift sensitized cells to lysis, but production of heat shock proteins exhibited protective effects. The results demonstrate that E-induced lysis can be divided into two distinct operations which may now be studied separately. They also emphasize a role for heat shock proteins under non-heat-shock conditions and suggest cautious interpretation of lysis phenomena in systems where E protein production is under control of a temperature-sensitive repressor.
机译：当细菌在E诱导时从30摄氏度转变为42摄氏度时，克隆的噬菌体phi X174的E蛋白对大肠杆菌的裂解速度比预期的要快。由于这种处理也诱导了热激反应，因此我们研究了热激蛋白对裂解的影响。 rpoH突变体对E裂解的敏感性更高，但是次级抑制突变使裂解抗性恢复到亲本水平，这表明sigma 32亚基本身并未直接增加裂解抗性。在30摄氏度下，五个热激基因（dnaK，dnaJ，groEL，groES和grpE）的突变体比其野生型亲本对突变更敏感。裂解敏感性的大小随突变和菌株背景而变化，其中dnaK，dnaJ和groES突变体始终表现出最大的敏感性。当在包含受tac启动子控制且带有rpoH +基因的质粒的细胞中人为诱导热休克蛋白过量生产时，就会发生针对裂解的扩展保护。 dnaK，dnaJ或groES的突变完全消除了这种保护作用，但grpE或groEL突变却没有。膜行为的改变可能解释了这样一个矛盾，即实际的温度变化使细胞对裂解敏感，但是热激蛋白的产生却显示出保护作用。结果表明，E诱导的裂解可分为两个不同的操作，现在可以分别进行研究。他们还强调了在非热休克条件下热激蛋白的作用，并建议对E蛋白产生受温度敏感阻遏物控制的系统中裂解现象的谨慎解释。

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