Duncan K, Coggins J R
Biochem J. 1986 Feb 15;234(1):49-57. doi: 10.1042/bj2340049.
Sub-cloning experiments aimed at precisely locating the E. coli aroA gene, which encodes the shikimate pathway enzyme 5-enolpyruvylshikimate 3-phosphate synthase, showed that in certain constructions, which remain capable of complementing an auxotrophic aroA mutation, expression of aroA is reduced. DNA sequence analysis revealed that a sequence approx. 1200 base pairs (bp) upstream of aroA is necessary for its expression. An open reading frame was identified in this region which encodes a protein of 362 amino acids with a calculated Mr of 39,834 and which ends 70 bp before the start of the aroA coding sequence. This gene has been identified as serC, the structural gene for 3-phosphoserine aminotransferase, an enzyme of the serine biosynthetic pathway. Both genes are expressed as a polycistronic message which is transcribed from a promotor located 58 bp upstream of serC. Evidence is presented which confirms that the aroA and serC genes constitute an operon which has the novel feature of encoding enzymes from two different amino acid biosynthetic pathways.
旨在精确定位大肠杆菌aroA基因（该基因编码莽草酸途径酶5-烯醇丙酮酸莽草酸-3-磷酸合酶）的亚克隆实验表明，在某些仍能够弥补营养缺陷型aroA突变的构建体中，aroA的表达会降低。DNA序列分析显示，aroA上游约1200个碱基对（bp）的序列对其表达是必需的。在此区域鉴定出一个开放阅读框，它编码一个由362个氨基酸组成、计算分子量为39,834的蛋白质，并且在aroA编码序列起始前70 bp处结束编码。该基因已被鉴定为serC，即3-磷酸丝氨酸转氨酶的结构基因，丝氨酸生物合成途径中的一种酶。这两个基因都作为一个多顺反子信息进行表达，该信息从位于serC上游58 bp处的启动子转录而来。本文提供的证据证实，aroA和serC基因构成一个操纵子，该操纵子具有编码来自两条不同氨基酸生物合成途径的酶这一新颖特征。
