Cloning and characterization of two catechol 1, 2-dioxygenase genes from Acinetobacter radioresistens S13

Two novel catechol 1,2-dioxygenase genes have been isolated from an Acinetobacter radioresistens strain that grows on phenol or benzoate as sole carbon and energy source. Designated as catAa and catAb , they encode proteins composed of 314 and 306 amino acids, whose deduced sequences indicate that they have approximately 53% identity, whereas their NH2-terminal and COOH-terminal regions have no sequences in common, this may explain their different thermal and pH stability. Polyclonal antibodies raised agaist an amino-terminal catAa peptide or the whole catAb protein were used to establish their inducible and differetial expression patters upon bacterial growth in pheno or benzoate. Tha catAa protein (Iso a) was induced by both phenol and benzoate though with different kinetics, whereas the catAb product (iso b) was constitutively produced at low levels that increased only during growth in the presence of benzoate.