Oriol E, Méndez-Alvarez S, Barbé J, Gibert I
Department of Genetics and Microbiology, Faculty of Sciences, Autonomous University of Barcelona, Spain.
Microbiology (Reading). 1996 Aug;142 ( Pt 8):2071-8. doi: 10.1099/13500872-142-8-2071.
The Rhodobacter sphaeroides 2.4.1 hisI gene, which encodes a phosphoribosyl-AMP-cyclohydrolase that catalyses the third step in the histidine biosynthetic pathway, has been isolated from a genomic library of this phototrophic bacterium by complementation of an Escherichia coli hisI mutant. Analysis of the nucleotide sequence of the R. sphaeroides hisI gene reveals that it encodes a deduced product of 119 aa with a predicted molecular mass of 13.4 kDa. In contrast to the situation in E. coli, the R. sphaeroides hisI gene encodes a unifunctional protein and it is not linked to the hisE gene. The absence of a single histidine operon like that of E. coli was confirmed by PFGE experiments and complementation analysis of a R. sphaeroides hisI mutant that was constructed by marker exchange. The location of hisI in the R. sphaeroides genome has been determined to be at map co-ordinate 2275 +/- 20 of chromosome l.
球形红细菌2.4.1的hisI基因编码一种磷酸核糖基-AMP-环水解酶，该酶催化组氨酸生物合成途径的第三步，通过互补大肠杆菌hisI突变体，已从这种光合细菌的基因组文库中分离出该基因。对球形红细菌hisI基因的核苷酸序列分析表明，它编码一个推导的119个氨基酸的产物，预测分子量为13.4 kDa。与大肠杆菌的情况不同，球形红细菌hisI基因编码一种单功能蛋白，且它不与hisE基因连锁。通过脉冲场凝胶电泳实验和通过标记交换构建的球形红细菌hisI突变体的互补分析，证实了不存在像大肠杆菌那样的单个组氨酸操纵子。已确定hisI在球形红细菌基因组中的位置位于染色体l的图谱坐标2275 +/- 20处。
