Cloning of a gene encoding hydroxyquinol 1,2-dioxygenase that catalyzes both intradiol and extradiol ring cleavage of catechol.
Two Escherichia coli transformants with catechol 1,2-dioxygenase activity were selected from a gene library of the benzamide-assimilating bacterium Arthrobacter species strain BA-5-17, which produces four catechol 1,2-dioxygenase isozymes. A DNA fragment isolated from one transformant contained a complete open reading frame (ORF). The deduced amino acid sequence of the ORF shared high identity with hydroxyquinol 1,2-dioxygenase. An enzyme expressed by the ORF was purified to homogeneity and characterized. When hydroxyquinol was used as a substrate, the purified enzyme showed 6.8-fold activity of that for catechol. On the basis of the sequence identity and substrate specificity of the enzyme, we concluded that the ORF encoded hydroxyquinol 1,2-dioxygenase. When catechol was used as a substrate, cis,cis-muconic acid and 2-hydroxymuconic 6-semialdehyde, which were products by the intradiol and extradiol ring cleavage activities, respectively, were produced. These results showed that the hydroxyquinol 1,2-dioxygenase reported here was a novel dioxygenase that catalyzed both the intradiol and extradiol cleavage of catechol.
Murakami
S
S
Department of Biofunctional Chemistry, Faculty of Agriculture, Kobe University, Japan.
Okuno
T
T
Matsumura
E
E
Takenaka
S
S
Shinke
R
R
Aoki
K
K
D000595:Amino Acid Sequence; D001483:Base Sequence; D002384:Catalysis; D002396:Catechols / Q000378:metabolism*; D003001:Cloning, Molecular; D049308:Dioxygenases; D006868:Hydrolysis; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010105:Oxygenases / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D010802:Phylogeny; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
D002396:Catechols; D010105:Oxygenases; D049308:Dioxygenases; C041894:hydroxyquinol 1,2-dioxygenase; C034221:catechol