Oxygen-dependent inactivation of glutamine phosphoribosylpyrophosphate amidotransferase in stationary-phase cultures of Bacillus subtilis
Oxygen-dependent inactivation of glutamine phosphoribosylpyrophosphate amidotransferase in stationary-phase cultures of Bacillus subtilis
复制标题
枯草芽孢杆菌稳定期培养物中谷氨酰胺磷酸核糖焦磷酸酰胺转移酶的氧依赖性失活
作者：
C. Turnbough;R. Switzer
谷氨酰胺磷酸核糖焦磷酸酰胺转移酶（ATase）活性在枯草芽孢杆菌的静止期细胞中迅速失活。APase的失活需要细胞快速生长的停止和氧气的存在。ATase在两种蛋白酶缺陷突变株中以与野生型相似的速率失活，并且在亲本菌株的厌氧无细胞提取物中稳定。这些结果表明，ATase的失活不是一般的蛋白水解的结果。ATase在静止期培养中的失活可以通过氧饥饿来抑制。这种氧需求并不反映对代谢能产生的依赖，但似乎是对分子氧的直接需求。腺苷酸酶的合成受到腺苷的抑制，只有在指数生长停止后才失活。添加氯霉素或利福平的指数期和静止期细胞不抑制ATase失活，这表明蛋白质或核糖核酸的合成是不需要的失活。AT酶在已耗尽所需氨基酸的细胞中的指数生长结束时失活。
Glutamine phosphoribosylpyrophosphate amidotransferase (ATase) activity is rapidly inactivated in stationary-phase cells of Bacillus subtilis. The inactivation of APase requires both the cessation of rapid cell growth and the presence of oxygen. ATase is inactivated in two protease-deficient mutant strains at a rate similar to that seen in the wild type, and is stable in anaerobic cell-free extracts of the parent strain. These results suggest that the inactivation of ATase is not the result of general proteolysis. The inactivation of ATase in stationary-phase cultures can be inhibited by oxygen starvation. This oxygen requirement does not reflect a dependence on the generation of metabolic energy, but appears to be a direct requirement for molecular oxygen. ATase synthesis is repressed by the addition of adenosine, and is inactivated only after the cessation of exponential growth. Addition of chloramphenicol or rifampin to exponential- and stationary-phase cells does not inhibit ATase inactivation, suggesting that protein or ribonucleic acid synthesis is not required for inactivation. ATase is inactivated at the end of exponential growth in cells that have exhausted a required amino acid.