In:
Journal of Bacteriology, American Society for Microbiology, Vol. 190, No. 15 ( 2008-08), p. 5199-5209
Abstract:
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(II) 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 μM) was competitive with hydroquinone. Online size-exclusion chromatography-mass spectrometry revealed that HQDO is an α2β2 heterotetramer of 112.4 kDa, which is composed of an α-subunit of 17.8 kDa and a β-subunit of 38.3 kDa. Each β-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.
Type of Medium:
Online Resource
ISSN:
0021-9193
,
1098-5530
Language:
English
Publisher:
American Society for Microbiology
Publication Date:
2008
detail.hit.zdb_id:
1481988-0
SSG:
12
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