Bascarán V, Hardisson C, Braña A F
Departamento de Biología Funcional, Facultad de Medicina, Universidad de Oviedo, Spain.
J Gen Microbiol. 1989 Sep;135(9):2465-74. doi: 10.1099/00221287-135-9-2465.
The levels of several enzymes involved in assimilation of different nitrogen compounds were investigated in Streptomyces clavuligerus in relation to the nitrogen source supplied to the cultures. Threonine dehydratase, serine dehydratase, proline dehydrogenase, histidase and urocanase were not decreased in the presence of ammonium. The latter two enzymes were induced by histidine in the culture medium, while proline dehydrogenase was induced by proline. Glutamine synthetase, urease and ornithine aminotransferase levels were higher with poor nitrogen sources and were repressed by ammonium. Arginase was induced by arginine and repressed by ammonium. Glutamine synthetase was rapidly inactivated upon addition of ammonium to the culture, and could be reactivated in vitro by treatment with snake venom phosphodiesterase, which suggested that adenylylation is involved in the inactivation. Three previously isolated mutants with abnormal glutamine synthetase activities showed pleiotropic effects on urease formation. All these data point to a mechanism controlling preferential utilization of some nitrogen sources in this species.
研究了棒状链霉菌中几种参与不同氮化合物同化的酶的水平，这些酶与供给培养物的氮源有关。在有铵存在的情况下，苏氨酸脱水酶、丝氨酸脱水酶、脯氨酸脱氢酶、组氨酸酶和尿刊酸酶的水平并未降低。后两种酶在培养基中由组氨酸诱导，而脯氨酸脱氢酶由脯氨酸诱导。谷氨酰胺合成酶、脲酶和鸟氨酸转氨酶的水平在氮源较差时较高，并受到铵的抑制。精氨酸酶由精氨酸诱导并受到铵的抑制。向培养物中添加铵后，谷氨酰胺合成酶迅速失活，并且可以通过用蛇毒磷酸二酯酶处理在体外重新激活，这表明腺苷酸化参与了失活过程。之前分离出的三个谷氨酰胺合成酶活性异常的突变体对脲酶的形成表现出多效性影响。所有这些数据都指向了一种控制该物种中某些氮源优先利用的机制。
