title: Identification of new enzymes potentially involved in anaerobic naphthalene degradation by the sulfate-reducing enrichment culture N47.
abstract: The sulfate-reducing highly enriched culture N47 is capable to anaerobically degrade naphthalene, 2-methylnaphthalene, and 2-naphthoic acid. A proteogenomic investigation was performed to elucidate the initial activation reaction of anaerobic naphthalene degradation. This lead to the identification of an alpha-subunit of a carboxylase protein that was two-fold up-regulated in naphthalene-grown cells compared to 2-methylnaphthalene-grown cells. The putative naphthalene carboxylase subunit showed 48% similarity to the anaerobic benzene carboxylase from an iron-reducing, benzene-degrading culture and 45% to alpha-subunit of phenylphosphate carboxylase of Aromatoleum aromaticum EbN1. A gene for the beta-subunit of putative naphthalene carboxylase was located nearby on the genome and was expressed with naphthalene. Similar to anaerobic benzene carboxylase, there were no genes for gamma- and delta-subunits of a putative carboxylase protein located on the genome which excludes participation in degradation of phenolic compounds. The genes identified for putative naphthalene carboxylase subunits showed only weak similarity to 4-hydroxybenzoate decarboxylase excluding ATP-independent carboxylation. Several ORFs were identified that possibly encode a 2-naphthoate-CoA ligase, which is obligate for activation before the subsequent ring reduction by naphthoyl-CoA reductase. One of these ligases was exclusively expressed on naphthalene and 2-naphthoic acid and might be the responsible naphthoate-CoA-ligase.
authors.affiliation: Institute of Groundwater Ecology, Helmholtz Zentrum München-German Research Center for Environmental Health, Ingolstädter Landstrasse 1, 85764, Neuherberg, Germany.
authors.forename: Franz D
authors.initials: FD
authors.lastname: Bergmann
authors.forename: Draženka
authors.initials: D
authors.lastname: Selesi
authors.forename: Rainer U
authors.initials: RU
authors.lastname: Meckenstock
mesh_terms: D000693:Anaerobiosis; D002262:Carboxy-Lyases / Q000378:metabolism*; D020564:Deltaproteobacteria / Q000201:enzymology* / Q000235:genetics; D015180:Electrophoresis, Gel, Two-Dimensional; D004591:Electrophoresis, Polyacrylamide Gel; D016680:Genome, Bacterial; D009281:Naphthalenes / Q000378:metabolism*; D012150:Polymorphism, Restriction Fragment Length; D020543:Proteome / Q000378:metabolism*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D009281:Naphthalenes; D020543:Proteome; D012336:RNA, Ribosomal, 16S; C031721:naphthalene; D002262:Carboxy-Lyases; C065828:4-hydroxybenzoate decarboxylase; C030037:2-naphthoic acid; C027384:2-methylnaphthalene