Cloning and Characterization of Two catA Genes in Acinetobacter lwoffii K24

다국어 초록 (Multilingual Abstract)

Two novel type I catechol 1,2-dioxygenases inducible on aniline media were isolated from Acinetobacter lwoffii K24. Although the two purified enzymes, CDI₁and CDI₂, had similar intradiol cleavage activities, they showed different substrate specificities for catechol analogs, physicochemical properties, and amino acid sequences. Two catA genes, catA₁and catA₂, encoding by CDI₁ and CD I₂, respectively, were isolated from the A. lwoffii K24 genomic library by using colony hybridization and PCR. Two DNA fragments containing the catA1 and catA₂ genes were located on separate regions of the chromosome. They contained open reading frames encoding 33.4-and 30.4-kDa proteins. The amino acid sequences of the two proteins matched well with previously determined sequences. Interestingly, further analysis of the two DNA fragments revealed the locations of the catB and catC genes as well. Moreover, the DNA fragment containing catA₁ had a cluster of genes in the order catB₁-catC₁-catA₁ while the catB₂-catA₂-catC₂ arrangement was found in the catA₂ DNA fragment. These results may provide an explanation of the different substrate specificities and physicochemical properties of CDI₁ and CDI₂.