Identification of three novel salicylate 1-hydroxylases involved in the phenanthrene degradation of Sphingobium sp. strain P2.
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.
Pinyakong
Onruthai
O
Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
Habe
Hiroshi
H
Yoshida
Takako
T
Nojiri
Hideaki
H
Omori
Toshio
T
D020561:Alphaproteobacteria / Q000201:enzymology* / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001673:Biodegradation, Environmental; D003001:Cloning, Molecular; D005798:Genes, Bacterial; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D006899:Mixed Function Oxygenases / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D016366:Open Reading Frames; D010616:Phenanthrenes / Q000378:metabolism*; D012336:RNA, Ribosomal, 16S / Q000235:genetics / Q000378:metabolism
D001426:Bacterial Proteins; D007527:Isoenzymes; D010616:Phenanthrenes; D012336:RNA, Ribosomal, 16S; D006899:Mixed Function Oxygenases; C022619:salicylate 1-monooxygenase