title: An unusual strategy for the anoxic biodegradation of phthalate.
abstract: In the past two decades, the study of oxygen-independent degradation of widely abundant aromatic compounds in anaerobic bacteria has revealed numerous unprecedented enzymatic principles. Surprisingly, the organisms, metabolites and enzymes involved in the degradation of o-phthalate (1,2-dicarboxybenzene), mainly derived from phthalate esters that are annually produced at the million ton scale, are sparsely known. Here, we demonstrate a previously unknown capacity of complete phthalate degradation in established aromatic compound-degrading, denitrifying model organisms of the genera Thauera, Azoarcus and 'Aromatoleum'. Differential proteome analyses revealed phthalate-induced gene clusters involved in uptake and conversion of phthalate to the central intermediate benzoyl-CoA. Enzyme assays provided in vitro evidence for the formation of phthaloyl-CoA by a succinyl-CoA- and phthalate-specific CoA transferase, which is essential for the subsequent oxygen-sensitive decarboxylation to benzoyl-CoA. The extreme instability of the phthaloyl-CoA intermediate requires highly balanced CoA transferase and decarboxylase activities to avoid its cellular accumulation. Phylogenetic analysis revealed phthaloyl-CoA decarboxylase as a novel member of the UbiD-like, (de)carboxylase enzyme family. Homologs of the encoding gene form a phylogenetic cluster and are found in soil, freshwater and marine bacteria; an ongoing global distribution of a possibly only recently evolved degradation pathway is suggested.
authors.affiliation: University of Freiburg, Institute for Biology II, Freiburg, Germany.
authors.forename: Christa
authors.initials: C
authors.lastname: Ebenau-Jehle
authors.affiliation: University of Freiburg, Institute for Biology II, Freiburg, Germany.
authors.forename: Mario
authors.initials: M
authors.lastname: Mergelsberg
authors.affiliation: University of Freiburg, Institute for Biology II, Freiburg, Germany.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Fischer
authors.affiliation: CEA, DRF, IG, Genoscope, Evry, France.|CNRS-UMR8030, Université d'Evry Val d'Essonne and Université Paris-Saclay, Evry, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Brüls
authors.affiliation: Helmholtz Centre for Environmental Research-UFZ, Department of Molecular Systems Biology, Leipzig, Germany.
authors.forename: Nico
authors.initials: N
authors.lastname: Jehmlich
authors.affiliation: Helmholtz Centre for Environmental Research-UFZ, Department of Molecular Systems Biology, Leipzig, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: von Bergen
authors.affiliation: University of Freiburg, Institute for Biology II, Freiburg, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Boll
mesh_terms: D000214:Acyl Coenzyme A / Q000235:genetics / Q000378:metabolism; D000693:Anaerobiosis; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001673:Biodegradation, Environmental; D015256:Coenzyme A-Transferases / Q000235:genetics / Q000378:metabolism; D005810:Multigene Family; D010795:Phthalic Acids / Q000378:metabolism*; D010802:Phylogeny
chemical_list: D000214:Acyl Coenzyme A; D001426:Bacterial Proteins; D010795:Phthalic Acids; C037817:benzoyl-coenzyme A; C032279:phthalic acid; C012046:succinyl-coenzyme A; D015256:Coenzyme A-Transferases