Tiedeman A A, DeMarini D J, Parker J, Smith J M
Seattle Biomedical Research Institute, Washington 98109.
J Bacteriol. 1990 Oct;172(10):6035-41. doi: 10.1128/jb.172.10.6035-6041.1990.
5'-Phosphoribosyl-5-aminoimidazole-4-N-succinocarboxamide synthetase (EC 6.3.2.6), encoded by the purC gene of Escherichia coli K-12, catalyzes the synthesis of 5'-phosphoribosyl-5-aminoimidazole-4-N-succinocarboxamide from 5'-phosphoribosyl-5-aminoimidazole-4-carboxylic acid. The mature protein, as deduced from the purC structural gene sequence, contains 237 amino acids and has a calculated Mr of 26,998. The control region of the purC gene was identified by primer extension mapping of the 5' end of the purC mRNA. The purC control region contains a binding site for and is regulated by the purine repressor, the product of the purR gene. An unusual feature of the 5' untranslated region of the purC mRNA is the presence of a repetitive extragenic palindrome sequence normally found in intercistronic or 3' untranslated regions. The DNA sequence was extended 1.281 kilobases upstream of the purC structural gene and overlapped with the previously determined dapA sequence. Termination of transcription from the dapA-purC intercistronic region may occur within the -35 region of the purC control region. The purC gene has been positioned on the E. coli restriction map and is transcribed in a counterclockwise direction.
5'-磷酸核糖基-5-氨基咪唑-4-N-琥珀酰胺羧基合成酶（EC 6.3.2.6），由大肠杆菌K-12的purC基因编码，催化从5'-磷酸核糖基-5-氨基咪唑-4-羧酸合成5'-磷酸核糖基-5-氨基咪唑-4-N-琥珀酰胺羧基。根据purC结构基因序列推导的成熟蛋白含有237个氨基酸，计算的分子量为26,998。通过对purC mRNA 5'端的引物延伸作图确定了purC基因的控制区域。purC控制区域含有嘌呤阻遏物（purR基因的产物）的结合位点并受其调控。purC mRNA 5'非翻译区的一个不寻常特征是存在通常在基因间或3'非翻译区发现的重复基因外回文序列。DNA序列在purC结构基因上游延伸了1.281千碱基，并与先前确定的dapA序列重叠。从dapA-purC基因间区域转录的终止可能发生在purC控制区域的-35区域内。purC基因已定位在大肠杆菌限制酶切图谱上，并以逆时针方向转录。
