title: Elucidation of the 4-hydroxyacetophenone catabolic pathway in Pseudomonas fluorescens ACB.
abstract: The catabolism of 4-hydroxyacetophenone in Pseudomonas fluorescens ACB is known to proceed through the intermediate formation of hydroquinone. Here, we provide evidence that hydroquinone is further degraded through 4-hydroxymuconic semialdehyde and maleylacetate to beta-ketoadipate. The P. fluorescens ACB genes involved in 4-hydroxyacetophenone utilization were cloned and characterized. Sequence analysis of a 15-kb DNA fragment showed the presence of 14 open reading frames containing a gene cluster (hapCDEFGHIBA) of which at least four encoded enzymes are involved in 4-hydroxyacetophenone degradation: 4-hydroxyacetophenone monooxygenase (hapA), 4-hydroxyphenyl acetate hydrolase (hapB), 4-hydroxymuconic semialdehyde dehydrogenase (hapE), and maleylacetate reductase (hapF). In between hapF and hapB, three genes encoding a putative intradiol dioxygenase (hapG), a protein of the Yci1 family (hapH), and a [2Fe-2S] ferredoxin (hapI) were found. Downstream of the hap genes, five open reading frames are situated encoding three putative regulatory proteins (orf10, orf12, and orf13) and two proteins possibly involved in a membrane efflux pump (orf11 and orf14). Upstream of hapE, two genes (hapC and hapD) were present that showed weak similarity with several iron(II)-dependent extradiol dioxygenases. Based on these findings and additional biochemical evidence, it is proposed that the hapC and hapD gene products are involved in the ring cleavage of hydroquinone.
authors.affiliation: Laboratory of Biochemistry, Wageningen University, Dreijenlaan 3, 6703 HA Wageningen, The Netherlands.
authors.forename: Mariëlle J H
authors.initials: MJ
authors.lastname: Moonen
authors.forename: Nanne M
authors.initials: NM
authors.lastname: Kamerbeek
authors.forename: Adrie H
authors.initials: AH
authors.lastname: Westphal
authors.forename: Sjef A
authors.initials: SA
authors.lastname: Boeren
authors.forename: Dick B
authors.initials: DB
authors.lastname: Janssen
authors.forename: Marco W
authors.initials: MW
authors.lastname: Fraaije
authors.forename: Willem J H
authors.initials: WJ
authors.lastname: van Berkel
mesh_terms: D000098:Acetophenones / Q000378:metabolism*; D000272:Adipates / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004798:Enzymes / Q000235:genetics; D005231:Fatty Acids, Unsaturated / Q000378:metabolism; D005288:Ferredoxins / Q000235:genetics; D006873:Hydroquinones / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008298:Maleates / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000235:genetics; D053858:Metabolic Networks and Pathways / Q000235:genetics*; D008969:Molecular Sequence Data; D005810:Multigene Family; D016366:Open Reading Frames; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000235:genetics; D010105:Oxygenases / Q000235:genetics; D011551:Pseudomonas fluorescens / Q000235:genetics* / Q000378:metabolism*; D017422:Sequence Analysis, DNA
chemical_list: D000098:Acetophenones; D000272:Adipates; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004798:Enzymes; D005231:Fatty Acids, Unsaturated; D005288:Ferredoxins; D006873:Hydroquinones; D008298:Maleates; D026901:Membrane Transport Proteins; C027316:3-oxoadipic acid; C011905:maleoylacetic acid; C002091:hydroxymuconic semialdehyde; D010105:Oxygenases; C400568:(chloro)hydroquinone 1, 2-dioxygenase; C427385:4-hydroxyacetophenone monooxygenase; C439587:extradiol dioxygenase; D044925:Oxidoreductases Acting on CH-CH Group Donors; C021530:maleylacetate reductase; C031335:4-hydroxyacetophenone; C031927:hydroquinone