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KMID : 0380219990320040399
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Journal of Biochemistry and Molecular Biology
1999 Volume.32 No. 4 p.399 ~ p.404
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The 2,3-Dihydroxybiphenyl 1,2-Dioxygenase Gene (phnQ) of Pseudomonas sp. DJ77: Nucleotide Sequence, Enzyme Assay, and Comparison with Isofunctional Dioxygenases
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Kim Seong-Jae
Shin Hee-Jung
Park Yong-Chjun
Kim Young-Soo
Min Kyung-Hee
Kim Young-Chang
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Abstract
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2,3-Dihydroxybiphenyl 1,2-dioxygenase (2,3-DHBD), which catalyzes the ring meta-cleavage of 2,3-dihydroxybiphenyl, is encoded by the phnQ gene of biphenyl- and phenanthrene-degrading Pseudomonas sp. strain DJ77. We determined the nucleotide sequence of a DNA fragment of 1497 base pairs which included the phnQ gene. The fragment lncluded an open reading frame of 903 base pairs to accommodate the enzyme. The predicted amino acid sequence of the enzyme subunit consisted of 300 residues. In front of the gene, a sequence resembling an E. coli promoter was identified, which led to constitutive expression of the cloned gene in E. coli. The deduced amino acid sequence of the PhnQ enzyme exhibited 85.6% identity with that of the corresponding enzyme in Sphingomonas yanoikuyae Q1 (formerly S. paucimobilis Q1) and 22.1% identity with that of catechol 1,2,3-dioxygenase from the same DJ77 strain. PhnQ showed broader substrate preference than previously-cloned PhnE, catechol 2,3-dioxygenase. Ten amino acid residues, considered to be important for the role of extradiol dioxygenases, were conserved.
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KEYWORD
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2,3-Dihydroxybiphenyl 1,2-Dioxygenase, phnQ, Strain DJ77, Substrate preference
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