COMPARATIVE-STUDIES OF GENES ENCODING THERMOSTABLE L-2-HALO ACID DEHALOGENASE FROM PSEUDOMONAS SP STRAIN-YL, OTHER DEHALOGENASES, AND 2 RELATED HYPOTHETICAL PROTEINS FROM ESCHERICHIA-COLI

We have determined the nucleotide sequence of the gene encoding thermo stable L-2-halo acid dehalogenase (L-DEX) from the 2-chloroacrylate-ut ilizable bacterium Pseudomonas sp. strain YL. The open reading frame c onsists of 696 nucleotides corresponding to 232 amino acid residues. T he protein molecular weight was estimated to be 26,179, which was in g ood agreement with the subunit molecular weight of the enzyme. The gen e was efficiently expressed in the recombinant Escherichia coli cells: the amount of L-DEX corresponds to about 49% of the total soluble pro teins. The predicted amino acid sequence showed a high level of simila rity to those of L-DEXs from other bacterial strains and haloacetate d ehalogenase H-2 from Moraxella sp. strain B (38 to 57% identity) but a very low level of similarity to those of haloacetate dehalogenase H-l from Moraxella sp. strain B (10%) and haloalkane dehalogenase from Xa nthobacter autotrophicus GJ10 (12%). By searching the protein amino ac id sequence database, we found two E. coil hypothetical proteins simil ar to the Pseudomonas sp. strain YL L-DEX (21 to 22%).