THE 4-HYDROXY-2-OXOVALERATE ALDOLASE AND ACETALDEHYDE DEHYDROGENASE (ACYLATING) ENCODED BY THE NAHM AND NAHO GENES OF THE NAPHTHALENE CATABOLIC PLASMID PWW60-22 PROVIDE FURTHER EVIDENCE OF CONSERVATION OF META-CLEAVAGE PATHWAY GENE-SEQUENCES

We report the complete nucleotide sequence and over-expression of the nahOM genes for the acetaldehyde dehydrogenase (acylating) and the 4-h ydroxy-2-oxovalerate aldolase from the meta pathway operon of the naph thalene catabolic plasmid pWW60-22 from Pseudomonas sp. NCIMB9816, Add itional partial sequence analysis of adjacent DNA shows the gene order within the operon to be nahNLOMK, identical to the order found for th e isofunctional genes in the meta pathway operons in the toluene/xylen e pathway of TOL plasmid pWWO and the phenol/methylphenol pathway of p VI150. The deduced amino acid sequences of NahO and NahM were signific antly homologous to the equivalent enzymes encoded by other Pseudomona s meta pathways, although both were the most divergent in each compari son. The nahOM genes were inserted downstream of the T7 promoter in th e expression vector pET3a and similar constructs were also made of the isofunctional regions from pVI150 (dmpFG) and TOL plasmid pDK1 (xy/QK ). High expression of all three gene pairs was detected by enzyme assa ys and by SDS-PAGE.