Identification of three novel salicylate 1-hydroxylases involved in the phenanthrene degradation of Sphingobium sp. strain P2

• Published in: Biochemical and biophysical research communications Vol. 301; no. 2; pp. 350 - 357
• Main Authors: Pinyakong, Onruthai, Habe, Hiroshi, Yoshida, Takako, Nojiri, Hideaki, Omori, Toshio
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 07.02.2003
• Subjects: Alphaproteobacteria - enzymology; Alphaproteobacteria - genetics; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Biodegradation, Environmental; Cloning, Molecular; Escherichia coli; Genes, Bacterial; Isoenzymes - genetics; Isoenzymes - metabolism; Mixed Function Oxygenases - genetics; Mixed Function Oxygenases - metabolism; Mutation; Open Reading Frames; Phenanthrene; Phenanthrenes - metabolism; Polycyclic aromatic hydrocarbon; RNA, Ribosomal, 16S - genetics; RNA, Ribosomal, 16S - metabolism; Salicylate 1-hydroxylase; Sphingobium; Sphingobium sp; Sphingomonads; Sphingobium sp; Phenanthrene; Salicylate 1-hydroxylase; Sphingomonads; Polycyclic aromatic hydrocarbon
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/S0006-291X(02)03036-X

Five sets of large and small subunits of terminal oxygenase ( ahdA1[ a– e] and ahdA2[ a– e]) and a single gene set encoding ferredoxin ( ahdA3) and ferredoxin reductase ( ahdA4) were found to be scattered through 15.8- and 14-kb DNA fragments of phenanthrene-degrading Sphingobium sp. strain P2. RT-PCR analysis indicated the inducible and specific expression of ahdA3, ahdA4, and three sets of genes for terminal oxygenase ( ahdA1[ c– e] and ahdA2[ c– e]) in this strain grown on phenanthrene. The biotransformation experiments with resting cells of Escherichia coli JM109 harboring recombinant ahd genes revealed that AhdA2cA1c, AhdA1dA2d, and AhdA1eA2e can all function as a salicylate 1-hydroxylase which converts salicylate, a metabolic intermediate of phenanthrene, to catechol in cooperation with the electron transport proteins AhdA3A4. The first two oxygenases exhibited a broad range of substrate specificities such that they also catalyzed the hydroxylation of methyl- and chloro-substituted salicylates to produce their corresponding substituted catechols.