Bordetella sp. 10d produces a novel dioxygenase catalyzing the meta-cleavage of 4-amino-3-hydroxybenzoic acid, 4-amino-3-hydroxybenzoate 2,3-dioxygenase (4A3HBA23D). A gene encoding 4A3HBA23D was cloned and named ahdA. The deduced amino acid sequence of ahdA showed 29.2-24.2% identities to those of prokaryotic and eukaryotic 3-hydoxybenzoate 3,4-dioxygenases in reported meta-cleavage dioxygenases. However, no identities were observed in the amino-terminal sequences of the first 29 amino acid residues. An ORF was found downstream of ahdA. The deduced amino acid sequence of the ORF showed identities to those of LysR family regulators involved in protocatechuate metabolism and contained motifs conserved in the regulators. On the basis of these results, the ORF was named ahdR encoding a putative LysR family regulator. The transcription start point of ahdA was localized 414-bp upstream of the start codon of ahdA. Two DNA-binding motifs of LysR family regulators were found upstream of the transcription start point. These observations suggest that a LysR family regulator encoded by ahdR regulates the expression of ahdA. (C) 2003 Elsevier Inc. All rights reserved.