Streptomyces, the most important group of industrial microorganisms, is harvested in liquid cultures for the production of two-thirds of all clinically relevant secondary metabolites. It is demonstrated here that the growth of Streptomyces coelicolor A3(2) is impacted by the deletion of the alanine dehydrogenase (ALD), an essential enzyme that plays a central role in the carbon and nitrogen metabolism. A long lag-phase growth followed by a slow exponential growth of S. coelicolor due to ALD gene deletion was observed in liquid yeast extract mineral salt culture. The slow lag-phase growth was replaced by the normal wild-type like growth by ALD complementation engineering. The ALD enzyme from S. coelicolor was also heterologously cloned and expressed in Escherichia coli for characterization. The optimum enzyme activity for the oxidative deamination reaction was found at 30°C, pH 9.5 with a catalytic efficiency, k_cat/K_M, of 2.0 ± 0.1 mM^–1 s^–1. The optimum enzyme activity for the reductive amination reaction was found at 30°C, pH 9.0 with a catalytic efficiency, k_cat/K_M, of 1.9 ± 0.1 mM^–1 s^–1.
J Mol Microbiol Biotechnol

中文翻译：

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丙氨酸脱氢酶的表征及其对液体培养中链霉菌coelicolorA3（2）发育的影响。

链霉菌是最重要的工业微生物群，是在液体培养物中收获的，用于生产所有临床相关次生代谢产物的三分之二。在此证明，链霉菌A3（2）的生长受到丙氨酸脱氢酶（ALD）的缺失的影响，丙氨酸脱氢酶是在碳和氮代谢中起关键作用的必需酶。在液态酵母提取物矿物盐培养物中观察到由于ALD基因缺失而导致的长滞后期期生长，然后是慢条斑沙门氏菌指数生长。缓慢的滞后阶段生长被ALD互补工程替代为正常的野生型生长。来自天蓝色链霉菌的ALD酶还异源地克隆了其并在大肠杆菌中表达以进行表征。在30°C，pH 9.5的条件下，发现了用于氧化脱氨反应的最佳酶活性，催化效率k _cat / K _M为2.0±0.1 mM ^–1 s ^–1。发现还原胺化反应的最佳酶活性是在30°C，pH 9.0时，催化效率k _cat / K _M为1.9±0.1 mM ^–1 s ^–1。
微生物微生物学杂志