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Detection of quorum-sensing-related molecules in Vibrio scophthalmi.

García-Aljaro C, Eberl L, Riedel K, Blanch AR - BMC Microbiol. (2008)

Bottom Line: This observation was further supported by the decrease in the presence of these signal molecules after cloning and expression of lactonase AiiA from Bacillus cereus in the V. scophthalmi strains.One of the signal molecules was identified as N-(3-hydroxy dodecanoyl)-L-homoserine lactone.Analysis of the translated sequence revealed that the sequenced luxS gene carried the conserved domain, which is common to luxS sequences found in other species, and which is essential for LuxS enzymatic activity.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Microbiology, University of Barcelona, Barcelona, Spain. cristina.garcia@cnm.es

ABSTRACT

Background: Cell-to-cell communication (also referred to as quorum sensing) based on N-acyl-homoserine lactones (AHLs) is a widespread response to environmental change in Gram-negative bacteria. AHLs seem to be highly variable, both in terms of the acyl chain length and in the chemical structure of the radicals. Another quorum sensing pathway, the autoinducer-2-based system, is present both in Gram-positive and Gram-negative bacteria. In this study the presence of signal molecules belonging to both quorum sensing signalling pathways was analysed in the marine symbiotic species Vibrio scophthalmi.

Results: Three AHL-like signal molecules were detected in V. scophthalmi supernatants with the Agrobacterium tumefaciens sensor assay. This observation was further supported by the decrease in the presence of these signal molecules after cloning and expression of lactonase AiiA from Bacillus cereus in the V. scophthalmi strains. One of the signal molecules was identified as N-(3-hydroxy dodecanoyl)-L-homoserine lactone. V. scophthalmi was also shown to carry a functional LuxS synthase. The coding sequence for a luxS-like gene was obtained showing a maximum similarity of 78% with Vibrio vulnificus. Analysis of the translated sequence revealed that the sequenced luxS gene carried the conserved domain, which is common to luxS sequences found in other species, and which is essential for LuxS enzymatic activity.

Conclusion: The data are consistent with the presence of quorum-sensing signal molecules from both AHL- and autoinducer 2-based quorum sensing systems in V. scophthalmi, which are homologous to others previously described in various Vibrio species. How this bacterium interacts with other bacteria and eukaryotic cells to compete ecologically with other intestinal bacteria present in the fish Scophthalmus maximus warrants further investigation.

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Effects of aiiA gene introduction in V. scophthalmi in the reduction of the AHL levels detected in a TLC assay following exposure to the sensor strain A. tumefaciens NTL4(pZLR4). Lane 1: V. scophthalmi A089; lane 2: V. scophthalmi A089 pACYC184-aiiA; lane 3 V. scophthalmi A102; lane 4: V. scophthalmi A102-aiiA; lane 5: V. scophthalmi A102 control strain with the pACYC184 plasmid, but without the aiiA gene.
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Figure 3: Effects of aiiA gene introduction in V. scophthalmi in the reduction of the AHL levels detected in a TLC assay following exposure to the sensor strain A. tumefaciens NTL4(pZLR4). Lane 1: V. scophthalmi A089; lane 2: V. scophthalmi A089 pACYC184-aiiA; lane 3 V. scophthalmi A102; lane 4: V. scophthalmi A102-aiiA; lane 5: V. scophthalmi A102 control strain with the pACYC184 plasmid, but without the aiiA gene.

Mentions: In order to confirm the presence of AHLs, AHL-derived or AHL-regulated substances in the supernatant of Vibrio scophthalmi, the lactonase gene aiiA from the Bacillus cereus strain A24 was subcloned into the pACYC184 plasmid and then electroporated into E. coli DH5α. This plasmid was subsequently transferred to the Vibrio strain by conjugation. We utilized two strains for those experiments addressing heterologous expression: V. scophthalmi A089 and V. scophthalmi A102. As measured by both, diffusion assays in agar plates and TLC, expression of the aiiA gene in both strains reduced autoinducer accumulation (Fig. 3). We constructed a control strain by conjugating the pACYC184 plasmid without the aiiA gene. As this control strain showed no AHL reduction, we attributed the decreased AHL production in recombinant strains to heterologous expression of the lactonase gene, confirming that these three putative autoinducers possessed an AHL-like structure or were AHL-regulated.


Detection of quorum-sensing-related molecules in Vibrio scophthalmi.

García-Aljaro C, Eberl L, Riedel K, Blanch AR - BMC Microbiol. (2008)

Effects of aiiA gene introduction in V. scophthalmi in the reduction of the AHL levels detected in a TLC assay following exposure to the sensor strain A. tumefaciens NTL4(pZLR4). Lane 1: V. scophthalmi A089; lane 2: V. scophthalmi A089 pACYC184-aiiA; lane 3 V. scophthalmi A102; lane 4: V. scophthalmi A102-aiiA; lane 5: V. scophthalmi A102 control strain with the pACYC184 plasmid, but without the aiiA gene.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2527009&req=5

Figure 3: Effects of aiiA gene introduction in V. scophthalmi in the reduction of the AHL levels detected in a TLC assay following exposure to the sensor strain A. tumefaciens NTL4(pZLR4). Lane 1: V. scophthalmi A089; lane 2: V. scophthalmi A089 pACYC184-aiiA; lane 3 V. scophthalmi A102; lane 4: V. scophthalmi A102-aiiA; lane 5: V. scophthalmi A102 control strain with the pACYC184 plasmid, but without the aiiA gene.
Mentions: In order to confirm the presence of AHLs, AHL-derived or AHL-regulated substances in the supernatant of Vibrio scophthalmi, the lactonase gene aiiA from the Bacillus cereus strain A24 was subcloned into the pACYC184 plasmid and then electroporated into E. coli DH5α. This plasmid was subsequently transferred to the Vibrio strain by conjugation. We utilized two strains for those experiments addressing heterologous expression: V. scophthalmi A089 and V. scophthalmi A102. As measured by both, diffusion assays in agar plates and TLC, expression of the aiiA gene in both strains reduced autoinducer accumulation (Fig. 3). We constructed a control strain by conjugating the pACYC184 plasmid without the aiiA gene. As this control strain showed no AHL reduction, we attributed the decreased AHL production in recombinant strains to heterologous expression of the lactonase gene, confirming that these three putative autoinducers possessed an AHL-like structure or were AHL-regulated.

Bottom Line: This observation was further supported by the decrease in the presence of these signal molecules after cloning and expression of lactonase AiiA from Bacillus cereus in the V. scophthalmi strains.One of the signal molecules was identified as N-(3-hydroxy dodecanoyl)-L-homoserine lactone.Analysis of the translated sequence revealed that the sequenced luxS gene carried the conserved domain, which is common to luxS sequences found in other species, and which is essential for LuxS enzymatic activity.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Microbiology, University of Barcelona, Barcelona, Spain. cristina.garcia@cnm.es

ABSTRACT

Background: Cell-to-cell communication (also referred to as quorum sensing) based on N-acyl-homoserine lactones (AHLs) is a widespread response to environmental change in Gram-negative bacteria. AHLs seem to be highly variable, both in terms of the acyl chain length and in the chemical structure of the radicals. Another quorum sensing pathway, the autoinducer-2-based system, is present both in Gram-positive and Gram-negative bacteria. In this study the presence of signal molecules belonging to both quorum sensing signalling pathways was analysed in the marine symbiotic species Vibrio scophthalmi.

Results: Three AHL-like signal molecules were detected in V. scophthalmi supernatants with the Agrobacterium tumefaciens sensor assay. This observation was further supported by the decrease in the presence of these signal molecules after cloning and expression of lactonase AiiA from Bacillus cereus in the V. scophthalmi strains. One of the signal molecules was identified as N-(3-hydroxy dodecanoyl)-L-homoserine lactone. V. scophthalmi was also shown to carry a functional LuxS synthase. The coding sequence for a luxS-like gene was obtained showing a maximum similarity of 78% with Vibrio vulnificus. Analysis of the translated sequence revealed that the sequenced luxS gene carried the conserved domain, which is common to luxS sequences found in other species, and which is essential for LuxS enzymatic activity.

Conclusion: The data are consistent with the presence of quorum-sensing signal molecules from both AHL- and autoinducer 2-based quorum sensing systems in V. scophthalmi, which are homologous to others previously described in various Vibrio species. How this bacterium interacts with other bacteria and eukaryotic cells to compete ecologically with other intestinal bacteria present in the fish Scophthalmus maximus warrants further investigation.

Show MeSH
Related in: MedlinePlus