Hydroquinone dioxygenase from Pseudomonas fluorescens ACB: A novel member of the family of non-heme iron (II)-dependent dioxygenases
Hydroquinone 1,2-dioxygenase (HQDO), an enzyme involved in the catabolism of 4-hydroxyacetophenone in Pseudomonas fluorescens ACB, was purified to apparent homogeneity. Ligandation with 4-hydroxybenzoate prevented the enzyme from irreversible inactivation. HQDO was activated by iron (H) ions and catalyzed the ring fission of a wide range of hydroquinones to the corresponding 4-hydroxymuconic semialdehydes. HQDO was inactivated by 2,2'-dipyridyl, o-phenanthroline, and hydrogen peroxide and inhibited by phenolic compounds. The inhibition with 4-hydroxybenzoate (K-i = 14 mu M) was competitive with hydroquinone. Online size-exclusion chromatography mass spectrometry revealed that HQDO is an alpha 2 beta 2 heterotetramer of 112.4 kDa, which is composed of an alpha-subunit of 17.8 kDa and a beta-subunit of 38.3 kDa. Each beta-subunit binds one molecule of 4-hydroxybenzoate and one iron(II) ion. N-terminal sequencing and peptide mapping and sequencing based on matrix-assisted laser desorption ionization-two-stage time of flight analysis established that the HQDO subunits are encoded by neighboring open reading frames (hapC and hapD) of a gene cluster, implicated to be involved in 4-hydroxyacetophenone degradation. HQDO is a novel member of the family of nonheme-iron(II)-dependent dioxygenases. The enzyme shows insignificant sequence identity with known dioxygenases.
| Main Authors: | , , , , , , , |
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| Format: | Article/Letter to editor biblioteca |
| Language: | English |
| Subjects: | 2-aminophenol 1,6-dioxygenase, 4-hydroxyacetophenone monooxygenase, baeyer-villiger oxidation, chlorinated acetophenones, crystal-structure, gentisate 1,2, hydroxyquinol 1,2-dioxygenase, of-flight instrument, p-nitrophenol, protocatechuate 4,5-dioxygenase, |
| Online Access: | https://research.wur.nl/en/publications/hydroquinone-dioxygenase-from-pseudomonas-fluorescens-acb-a-novel |
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