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首页> 外文期刊>Journal of bacteriology >Effects of crp mutations on adenosine 3',5'-monophosphate metabolism in Salmonella typhimurium.
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Effects of crp mutations on adenosine 3',5'-monophosphate metabolism in Salmonella typhimurium.

机译：crp突变对鼠伤寒沙门氏菌3'，5'-一磷酸腺苷代谢的影响。

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Wild-type Salmonella typhimurium could not grow with exogenous cyclic adenosine 3',5'-monophosphate (AMP) as the sole source of phosphate, but mutants capable of cyclic AMP utilization could be isolated provided the parental strain contained a functional cyclic AMP phosphodiesterase.All cyclic AMP-utilizing mutants had the growth and fermentation properties of cyclic AMP receptor protein (crp) mutants, and some lacked cyclic AMP binding activity in vitro. The genetic defect in each such mutant was due to a single point mutation, which was co-transducible with cysG. crp mutants isolated by alternative procedures also exhibited the capacity to utilize cyclic AMP. crp mutants synthesized cyclic AMP at increased rates and contained enhanced cellular cyclic AMP levels relative to the parental strains, regardless of whether or not cyclic AMP phosphodiesterase was active. Moreover, adenylate cyclase activity in vivo was less sensitive to regulation by glucose, possibly because the enzyme II complexes of the phosphotransferase system, responsible for glucose transport and phosphorylation, could not be induced to maximal levels. This possibility was strengthened by the observation that enzyme II activity (measured both in vitro by sugar phosphorylation and in vivo by sugar transport and chemotaxis) was inducible in the parental strain but not in crp mutants. The results suggest that the cyclic AMP receptor protein regulates cyclic AMP metabolism as well as catabolic enzyme synthesis.
机译：野生型鼠伤寒沙门氏菌不能以外源性环状腺苷3'，5'-单磷酸盐（AMP）作为唯一的磷酸盐来源生长，但如果亲本菌株含有功能性环状AMP磷酸二酯酶，则可以分离出能够利用AMP的突变体。所有利用环状AMP的突变体均具有环状AMP受体蛋白（crp）突变体的生长和发酵特性，并且其中一些缺乏体外的环状AMP结合活性。每个此类突变体的遗传缺陷是由于单点突变，可与cysG共转导。通过替代方法分离的crp突变体也显示出利用环AMP的能力。相对于亲本菌株，crp突变体以更高的速率合成环状AMP，并且包含增强的细胞环状AMP水平，无论环状AMP磷酸二酯酶是否活跃。此外，体内腺苷酸环化酶的活性对葡萄糖的调节较不敏感，这可能是由于不能将导致葡萄糖转运和磷酸化的磷酸转移酶系统的酶II复合物诱导到最大水平。通过观察到在亲本菌株中可诱导酶II活性（通过糖磷酸化作用在体外测量，以及在体内通过糖转运和趋化性测量）来增强这种可能性，而在crp突变体中则不能。结果表明，环状AMP受体蛋白调节环状AMP的代谢以及分解代谢酶的合成。

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