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早期的遗传分析表明鼠伤寒沙门氏菌嘌呤核苷酸从头合成途径中AICAI Transformylase、IMP Cyclohydrolase和GAR合成酶分别由三个结构基因purJ、purH和purD编码。这三个结构基因构成一个操纵子,定位于遗传图90分钟”,2J。但最近对大肠杆菌这一操纵子的核苷酸序列测定及其编码产物的研究,发现在大肠杆菌中为上述三个酶编码的结构基因只有purH和purD,并不存在purJ结构基因。新近Chopra报道了鼠伤寒沙门氏菌位于purH内的EcoRI切点下游直至purD终止密码的核苷酸序列,同源性比较分析显示鼠伤寒沙门氏菌这部分序列分别与大肠杆菌的purH和purD有85％和88％的同源性。尽管如此,对鼠伤寒沙门氏菌中究竟有无purJ
Early genetic analysis indicated that AICAI Transformylase, IMP Cyclohydrolase and GAR synthetase were encoded by the three structural genes purJ, purH and purD, respectively, in an S. typhimurium purine nucleotide de novo synthesis pathway. These three structural genes constitute an operon, located in the genetic map 90 minutes, "2J. But recently, the operon of E. coli nucleotide sequence determination and its coding products were found in E. coli for the three The enzyme-encoded structural gene is only purH and purD, and no purJ structural gene is present.New Chopra reports the nucleotide sequence of Salmonella typhimurium located downstream of the EcoRI cleavage site in purH up to the purD stop codon, and homology comparative analysis showed that the murine Salmonella typhi this part of the sequence were E. coli purH and purD 85% and 88% homology, however, whether there is Salmonella typhimurium purJ