title: Two enzymes of a complete degradation pathway for linear alkylbenzenesulfonate (LAS) surfactants: 4-sulfoacetophenone Baeyer-Villiger monooxygenase and 4-sulfophenylacetate esterase in Comamonas testosteroni KF-1.
abstract: Complete biodegradation of the surfactant linear alkylbenzenesulfonate (LAS) is accomplished by complex bacterial communities in two steps. First, all LAS congeners are degraded into about 50 sulfophenylcarboxylates (SPC), one of which is 3-(4-sulfophenyl)butyrate (3-C(4)-SPC). Second, these SPCs are mineralized. 3-C(4)-SPC is mineralized by Comamonas testosteroni KF-1 in a process involving 4-sulfoacetophenone (SAP) as a metabolite and an unknown inducible Baeyer-Villiger monooxygenase (BVMO) to yield 4-sulfophenyl acetate (SPAc) from SAP (SAPMO enzyme); hydrolysis of SPAc to 4-sulfophenol and acetate is catalyzed by an unknown inducible esterase (SPAc esterase). Transcriptional analysis showed that one of four candidate genes for BVMOs in the genome of strain KF-1, as well as an SPAc esterase candidate gene directly upstream, was inducibly transcribed during growth with 3-C(4)-SPC. The same genes were identified by enzyme purification and peptide fingerprinting-mass spectrometry when SAPMO was enriched and SPAc esterase purified to homogeneity by protein chromatography. Heterologously overproduced pure SAPMO converted SAP to SPAc and was active with phenylacetone and 4-hydroxyacetophenone but not with cyclohexanone and progesterone. SAPMO showed the highest sequence homology to the archetypal phenylacetone BVMO (57%), followed by steroid BVMO (55%) and 4-hydroxyacetophenone BVMO (30%). Finally, the two pure enzymes added sequentially, SAPMO with NADPH and SAP, and then SPAc esterase, catalyzed the conversion of SAP via SPAc to 4-sulfophenol and acetate in a 1:1:1:1 molar ratio. Hence, the first two enzymes of a complete LAS degradation pathway were identified, giving evidence for the recruitment of members of the very versatile type I BVMO and carboxylester hydrolase enzyme families for the utilization of a xenobiotic compound by bacteria.
authors.affiliation: Department of Biology, University of Konstanz, Konstanz, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Weiss
authors.forename: Karin
authors.initials: K
authors.lastname: Denger
authors.forename: Thomas
authors.initials: T
authors.lastname: Huhn
authors.forename: David
authors.initials: D
authors.lastname: Schleheck
mesh_terms: D017738:Alkanesulfonic Acids / Q000378:metabolism*; D001711:Biotransformation; D020604:Comamonas testosteroni / Q000201:enzymology* / Q000235:genetics; D004950:Esterases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D013058:Mass Spectrometry; D053858:Metabolic Networks and Pathways / Q000235:genetics*; D006899:Mixed Function Oxygenases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D010455:Peptides / Q000032:analysis; D017386:Sequence Homology, Amino Acid; D013501:Surface-Active Agents / Q000378:metabolism*
chemical_list: D017738:Alkanesulfonic Acids; D010455:Peptides; D013501:Surface-Active Agents; C030641:alkylbenzyl sulfonic acid; D006899:Mixed Function Oxygenases; D004950:Esterases