Regulation of Serine Transhydroxymethylase Activity in Salmonella typhimurium
Regulation of Serine Transhydroxymethylase Activity in Salmonella typhimurium
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鼠伤寒沙门氏菌丝氨酸转羟甲基酶活性的调节
DOI：
10.1128/jb.120.3.1017-1025.1974
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发表时间：
1974
影响因子：
3.2
通讯作者：
J. Brenchley
中科院分区：
文献类型：
--
作者：
G. Stauffer;C. A. Baker;J. Brenchley
丝氨酸转羟甲基化酶（EC 2.1.2.1.; L-丝氨酸：四氢叶酸-5，10-羟甲基转移酶）在鼠伤寒沙门氏菌LT 2中的作用。我们的研究结果表明，限制甲硫氨酸营养缺陷型甲硫氨酸不会导致这种酶的解阻遏大肠杆菌的报告。然而，当S.鼠伤寒杆菌细胞在补充有丝氨酸、甘氨酸、甲硫氨酸、腺嘌呤、鸟嘌呤和胸腺嘧啶的葡萄糖基本培养基中生长。没有这些化合物单独添加到生长培养基中产生超过42%的野生型酶活性的减少。化合物组合的这种增强的抑制表明这种酶的累积抑制形式。生长的丝氨酸和胸腺嘧啶营养缺陷型，与各自的要求，每个限制，并没有导致酶活性增加。然而，生长的嘌呤营养缺陷型与限制量的鸟嘌呤或肌苷导致酶活性的五至七倍的增加。第二个条件是每毫升加入0.5 μg甲氧苄啶（一种二氢叶酸还原酶活性抑制剂），可导致显著的去阻遏（增加4倍），高于在基本培养基中生长的细胞所观察到的水平。（关于这项工作的部分报告在1974年的美国微生物学会会议上提出。
The regulation of serine transhydroxymethylase (EC 2.1.2.1.; l-serine:tetrahydrofolic-5,10-hydroxymethyltransferase) has been investigated in Salmonella typhimurium LT2. Our results indicate that limitation of a methionine auxotroph for methionine does not cause derepression of this enzyme as reported for Escherichia coli. However, a sixfold decrease in specific activity was observed when S. typhimurium cells were grown in glucose minimal medium supplemented with serine, glycine, methionine, adenine, guanine, and thymine. None of these compounds added to the growth medium individually produced more than a 42% reduction of wild-type enzyme activity. This enhanced repression by the combination of compounds suggests a form of cumulative repression of this enzyme. Growth of serine and thymine auxotrophs, with the respective requirement of each limiting, did not result in increased enzyme activity. However, growth of a purine auxotroph with a limiting amount of either guanine or inosine resulted in a five- to sevenfold increase in enzyme activity. A second condition causing significant derepression (fourfold increase) above the levels observed with cells grown in minimal medium was the addition of 0.5 μg of trimethoprim per ml, an inhibitor of the dihydrofolate reductase activity. (A partial report on this work was presented at 1974 meeting of the American Society for Microbiology.)