Elucidation of the 4-hydroxyacetophenone catabolic pathway in Pseudomonas fluorescens ACB.
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.
Moonen
Mariëlle J H
MJ
Laboratory of Biochemistry, Wageningen University, Dreijenlaan 3, 6703 HA Wageningen, The Netherlands.
Kamerbeek
Nanne M
NM
Westphal
Adrie H
AH
Boeren
Sjef A
SA
Janssen
Dick B
DB
Fraaije
Marco W
MW
van Berkel
Willem J H
WJ
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
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