DNA-SEQUENCE CONSERVATION AT THE GENE LEVEL IN A CONSERVED CHROMOSOMAL SEGMENT IN 2 PSEUDOMONAS SPECIES

A comparative analysis has been made of the DNA sequences of the isofu nctional genes encoding N-acetylglutamate synthase of the arginine bio synthetic pathway of the bacterial species Pseudomonas aeruginosa and Pseudomonas putida. Overall homologies of 81% and 84% at the nucleotid e and deduced amino acid sequence levels, respectively, were observed. This high homology was also reflected in the strikingly similar hydro pathy profiles of the encoded proteins; patterns of codon usage, inclu ding rare codon usage; and amino acid composition of the proteins. Thi s high level of homology at the DNA sequence level is consistent with the location of these genes in the genetically conserved chromosomal r egion (called auxotrophic-rich region) of the respective Pseudomonas s pecies. Despite chromosomal rearrangements identified in this region t he conservation observed at the chromosomal level between these Pseudo monas species is also maintained at the level of the DNA sequence, and in the deduced amino acid sequence, of the genes reported here and of six other pairs of genes of the tryptophan biosynthetic pathway, repo rted by others, which are also located within this chromosomal region.