Schlesinger S, Nester E W
J Bacteriol. 1969 Oct;100(1):167-75. doi: 10.1128/jb.100.1.167-175.1969.
We have isolated several mutants defective in the gene for tyrosyl-transfer ribonucleic acid (tRNA) synthetase (tyrS). One of these mutants is described in detail. It was isolated as a tyrosine auxotroph with defects both in the tyrosyl-tRNA synthetase and in the tyrosine biosynthetic enzyme, prephenate dehydrogenase. It also had derepressed levels of the tyrosine-specific 3-deoxy-d-arabinoheptulosonic acid-7-phosphate (DAHP) synthetase. The latter finding suggested that a wild-type tyrS gene was required for repression of the tyrosine biosynthetic enzymes. The following results demonstrated that this hypothesis was not correct. (i) When the defective tyrS gene was transferred to another strain, the tyrosine-specific DAHP synthetase in that strain was not derepressed, and (ii) two other mutants with defective tyrosyl-tRNA synthetases had repressed levels of the tyrosine biosynthetic enzymes. The tyrS gene was located near minute 32 on the Escherichia coli chromosome by interrupted mating experiments.
我们已经分离出了几种在酪氨酰 - 转移核糖核酸（tRNA）合成酶（tyrS）基因上有缺陷的突变体。其中一个突变体将被详细描述。它是作为酪氨酸营养缺陷型被分离出来的，在酪氨酰 - tRNA合成酶和酪氨酸生物合成酶——预苯酸脱氢酶方面都有缺陷。它的酪氨酸特异性3 - 脱氧 - D - 阿拉伯庚酮糖酸 - 7 - 磷酸（DAHP）合成酶水平也处于去阻遏状态。后一个发现表明，野生型tyrS基因对于酪氨酸生物合成酶的阻遏是必需的。以下结果表明这个假设是不正确的。（i）当有缺陷的tyrS基因转移到另一个菌株时，该菌株中的酪氨酸特异性DAHP合成酶并没有去阻遏，并且（ii）另外两个酪氨酰 - tRNA合成酶有缺陷的突变体，其酪氨酸生物合成酶水平处于阻遏状态。通过中断杂交实验，tyrS基因被定位在大肠杆菌染色体上靠近32分钟处。
