A variant quorum sensing system in Aeromonas veronii MTCC 3249.
We have investigated the quorum sensing control in Aeromonas veronii MTCC 3249, originally isolated as A. culicicola from the midgut of Culex quinquefasciatus. Based on biosensor assays, the bacterium showed constant production of multiple acyl-homoserine lactones (AHLs) with increasing cell-density. The luxRI gene homologs, acuR (A. culicicola transcriptional Regulator) and acuI (A. culicicola autoInducer) were successfully amplified by inverse-PCR. Sequence analysis indicated acuRI were divergent from all known quorum sensing gene homologs in Aeromonas. Two localized regions in the C-terminal autoinducer binding domain of acuR showed indels suggesting variations in autoinducer specificity. Further, only a single copy of the quorum sensing genes was detected, suggesting a tight regulation of mechanisms under its control. Chromatography and further chemical analysis identified two AHLs in the culture supernatant: 6-carboxy-HHL (homoadipyl homoserine lactone), a novel AHL, and N-tetradecanoylhomoserine lactone. The existence of a potentially variant quorum sensing system might therefore, reflect in some way the ecological strategies adopted by this bacterium in the mosquito midgut.
Microbial Culture Collection, National Centre for Cell Science, Pune, Maharashtra, India. jangidk@nccs.res.in
Kamlesh
K
Jangid
Perunninakulath S
PS
Parameswaran
Yogesh S
YS
Shouche
D000333:Aeromonas / Q000235:genetics / Q000502:physiology*; D001483:Base Sequence; D015139:Blotting, Southern; D002855:Chromatography, Thin Layer; D017931:DNA Primers; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D053038:Quorum Sensing; D012689:Sequence Homology, Nucleic Acid; D053719:Tandem Mass Spectrometry
D017931:DNA Primers; D004269:DNA, Bacterial