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 I.
- Chromosome mapping
- hisI gene
- Histidine biosynthesis
- Rhodobacter sphaeroides
Oriol, E., Méndez-Álvarez, S., Barbé, J., & Gibert, I. (1996). Cloning of the Rhodobacter sphaeroides hisI gene: Unifunctionality of the encoded protein and lack of linkage to other his genes. Microbiology, 142(8), 2071-2078. https://doi.org/10.1099/13500872-142-8-2071