title: A metagenomic study highlights phylogenetic proximity of quorum-quenching and xenobiotic-degrading amidases of the AS-family.
abstract: Quorum-sensing (QS) signals of the N-acylhomoserine lactone (NAHL) class are cleaved by quorum-quenching enzymes, collectively named NAHLases. Here, functional metagenomics allowed the discovery of a novel bacterial NAHLase in a rhizosphere that was treated with γ-caprolactone. As revealed by rrs-DGGE and rrs-pyrosequencing, this treatment increased the percentage of the NAHL-degrading bacteria and strongly biased the structure of the bacterial community, among which Azospirillum dominated. Among the 29 760 fosmids of the metagenomic library, a single one was detected that expressed the qsdB gene conferring NAHL-degradation upon E. coli and decreased QS-regulated virulence in Pectobacterium. Phylogenetic analysis of the 34 orfs of the fosmid suggested that it would belong to an unknown Proteobacterium - probably a γ-proteobacterium. qPCR quantification of the NAHLase-encoding genes attM, qsdA, and qsdB revealed their higher abundance in the γ-caprolactone-treated rhizosphere as compared to an untreated control. The purified QsdB enzyme exhibited amidase activity. QsdB is the first amidase signature (AS) family member exhibiting NAHLase-activity. Point mutations in the AS-family catalytic triad K-S-S abolished the NAHLase activity of QsdB. This study extends the diversity of NAHLases and highlights a common phylogenic origin of AS-family enzymes involved in the degradation of natural compounds, such as NAHLs, and xenobiotics, such as nylon and linuron.
authors.affiliation: Institut des Sciences du Végétal, UPR2355, Centre National de la Recherche Scientifique, Gif-sur-Yvette, France.
authors.forename: Mélanie
authors.initials: M
authors.lastname: Tannières
authors.forename: Amélie
authors.initials: A
authors.lastname: Beury-Cirou
authors.forename: Armelle
authors.initials: A
authors.lastname: Vigouroux
authors.forename: Samuel
authors.initials: S
authors.lastname: Mondy
authors.forename: Franck
authors.initials: F
authors.lastname: Pellissier
authors.forename: Yves
authors.initials: Y
authors.lastname: Dessaux
authors.forename: Denis
authors.initials: D
authors.lastname: Faure
mesh_terms: D054742:Acyl-Butyrolactones / Q000378:metabolism; D000581:Amidohydrolases / Q000378:metabolism*; D001419:Bacteria / Q000187:drug effects / Q000201:enzymology / Q000235:genetics; D055162:Biocatalysis / Q000187:drug effects; D001673:Biodegradation, Environmental; D044822:Biodiversity; D002208:Caproates / Q000494:pharmacology; D002265:Carboxylic Ester Hydrolases / Q000378:metabolism; D005798:Genes, Bacterial / Q000235:genetics; D007783:Lactones / Q000494:pharmacology; D056186:Metagenomics; D016366:Open Reading Frames / Q000235:genetics; D010802:Phylogeny; D020161:Physical Chromosome Mapping; D053038:Quorum Sensing / Q000187:drug effects / Q000235:genetics; D015262:Xenobiotics / Q000378:metabolism*
chemical_list: D054742:Acyl-Butyrolactones; D002208:Caproates; D007783:Lactones; D015262:Xenobiotics; C121056:caprolactone; D002265:Carboxylic Ester Hydrolases; C432003:N-acyl homoserine lactonase; D000581:Amidohydrolases