title: Genome sequencing-assisted identification and the first functional validation of N-acyl-homoserine-lactone synthases from the Sphingomonadaceae family.
abstract: BACKGROUND
  Members of the genus Novosphingobium have been isolated from a variety of environmental niches. Although genomics analyses have suggested the presence of genes associated with quorum sensing signal production e.g., the N-acyl-homoserine lactone (AHL) synthase (luxI) homologs in various Novosphingobium species, to date, no luxI homologs have been experimentally validated.
  
  
  METHODS
  In this study, we report the draft genome of the N-(AHL)-producing bacterium Novosphingobium subterraneum DSM 12447 and validate the functions of predicted luxI homologs from the bacterium through inducible heterologous expression in Agrobacterium tumefaciens strain NTL4. We developed a two-dimensional thin layer chromatography bioassay and used LC-ESI MS/MS analyses to separate, detect and identify the AHL signals produced by the N. subterraneum DSM 12447 strain.
  
  
  RESULTS
  Three predicted luxI homologs were annotated to the locus tags NJ75_2841 (NovINsub1), NJ75_2498 (NovINsub2), and NJ75_4146 (NovINsub3). Inducible heterologous expression of each luxI homologs followed by LC-ESI MS/MS and two-dimensional reverse phase thin layer chromatography bioassays followed by bioluminescent ccd camera imaging indicate that the three LuxI homologs are able to produce a variety of medium-length AHL compounds. New insights into the LuxI phylogeny was also gleemed as inferred by Bayesian inference.
  
  
  CONCLUSIONS
  This study significantly adds to our current understanding of quorum sensing in the genus Novosphingobium and provide the framework for future characterization of the phylogenetically interesting LuxI homologs from members of the genus Novosphingobium and more generally the family Sphingomonadaceae.
authors.affiliation: School of Science, Monash University Malaysia, Bandar Sunway, Selangor, Malaysia; Genomics Facility, Tropical Medicine Biology Platform, Monash University Malaysia, Bandar Sunway, Selangor, Malaysia.
authors.forename: Han Ming
authors.initials: HM
authors.lastname: Gan
authors.affiliation: Thomas H. Gosnell School of School of Life Sciences, Rochester Institute of Technology , Rochester , NY , USA.
authors.forename: Lucas K
authors.initials: LK
authors.lastname: Dailey
authors.affiliation: School of Life Sciences, Centre for Biomolecular Sciences, University of Nottingham , Nottingham , UK.
authors.forename: Nigel
authors.initials: N
authors.lastname: Halliday
authors.affiliation: School of Life Sciences, Centre for Biomolecular Sciences, University of Nottingham , Nottingham , UK.
authors.forename: Paul
authors.initials: P
authors.lastname: Williams
authors.affiliation: Thomas H. Gosnell School of School of Life Sciences, Rochester Institute of Technology , Rochester , NY , USA.
authors.forename: André O
authors.initials: AO
authors.lastname: Hudson
authors.affiliation: Thomas H. Gosnell School of School of Life Sciences, Rochester Institute of Technology , Rochester , NY , USA.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Savka
keywords: Acyl-homoserine lactones; LuxIR; N-acyl-homoserine lactone synthases; Novosphingobium; Phylogenetic; Quorum-sensing; Sphingomonadaceae; Two-dimensional thin-layer chromatography; Whole genome sequencing