Genomic organization of purK and purE in Brevibacterium ammoniagenes ATCC 6872 : purE locus provides a clue for genomic evolution

Abstract

From the genomic library of Brevibacterium ammoniagenes ATCC6872, the pitrE locus encoding 5′-phosphoribosyl-5-aminoimidazole (AIR) carboxylase (EC 4.1.1.21) was cloned and its nucleotide sequence was determined. From the sequence analysis, two distinct open reading frames (ORFs) in the sequence of the purE locus were identified as purK and purE genes (purK-purE). An in vivo translation experiment reconfirmed the purK and purE genes to be independent. The genomic organization in the purE locus of B. ammoniagenes is opposite to that of the bacteria Escherichia coli and Bacillus subtilis. However, it coincides with the fused genes (purKE) of higher organisms Sacckaromyces cerevisiae, Schizosaccharomyces pombe and Vigna aconitifolia. This suggests that the purE locus might be an intermediate form for genomic evolution of bacteria to higher organisms.