Cloning of the Rhodobacter sphaeroides hisL gene: unifunctionality of the encoded protein and lack of linkage to other his genes.
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.
Oriol
E
E
Department of Genetics and Microbiology, Faculty of Sciences, Autonomous University of Barcelona, Spain.
Méndez-Alvarez
S
S
Barbé
J
J
Gibert
I
I
D000595:Amino Acid Sequence; D000619:Aminohydrolases / Q000096:biosynthesis* / Q000235:genetics*; D001483:Base Sequence; D002874:Chromosome Mapping; D002876:Chromosomes, Bacterial; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D008040:Genetic Linkage; D015698:Genomic Library; D006639:Histidine / Q000096:biosynthesis*; D008969:Molecular Sequence Data; D010957:Plasmids; D011994:Recombinant Proteins / Q000096:biosynthesis; D015183:Restriction Mapping; D012242:Rhodobacter sphaeroides / Q000201:enzymology / Q000235:genetics*; D012486:Salmonella typhimurium / Q000235:genetics; D017386:Sequence Homology, Amino Acid
D011994:Recombinant Proteins; D006639:Histidine; D000619:Aminohydrolases; C022383:phosphoribosyl-AMP cyclohydrolase