PMID:19182778

Citation	Mandel, MJ, Wollenberg, MS, Stabb, EV, Visick, KL and Ruby, EG (2009) A single regulatory gene is sufficient to alter bacterial host range. Nature 458:215-8
Abstract	Microbial symbioses are essential for the normal development and growth of animals. Often, symbionts must be acquired from the environment during each generation, and identification of the relevant symbiotic partner against a myriad of unwanted relationships is a formidable task. Although examples of this specificity are well-documented, the genetic mechanisms governing it are poorly characterized. Here we show that the two-component sensor kinase RscS is necessary and sufficient for conferring efficient colonization of Euprymna scolopes squid by bioluminescent Vibrio fischeri from the North Pacific Ocean. In the squid symbiont V. fischeri ES114, RscS controls light-organ colonization by inducing the Syp exopolysaccharide, a mediator of biofilm formation during initial infection. A genome-level comparison revealed that rscS, although present in squid symbionts, is absent from the fish symbiont V. fischeri MJ11. We found that heterologous expression of RscS in strain MJ11 conferred the ability to colonize E. scolopes in a manner comparable to that of natural squid isolates. Furthermore, phylogenetic analyses support an important role for rscS in the evolution of the squid symbiosis. Our results demonstrate that a regulatory gene can alter the host range of animal-associated bacteria. We show that, by encoding a regulator and not an effector that interacts directly with the host, a single gene can contribute to the evolution of host specificity by switching 'on' pre-existing capabilities for interaction with animal tissue.
Links	PubMed PMC2713604 Online version:10.1038/nature07660
Keywords	Aliivibrio fischeri/genetics; Aliivibrio fischeri/growth & development; Animal Structures/microbiology; Animals; Biofilms/growth & development; Decapodiformes/microbiology; Molecular Sequence Data; Pacific Ocean; Phylogeny; Polysaccharides, Bacterial/genetics; Polysaccharides, Bacterial/metabolism; Protein Kinases/genetics; Protein Kinases/metabolism; Symbiosis/genetics; Symbiosis/physiology
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
VIBFI:Q9ANY0		GO:0075294: positive regulation by symbiont of entry into host	ECO:0000314:		P		Figure 1e shows that a plasmid containing RscS is sufficient to allow a non-symbiotic strain of V. fischeri to colonize the light organ of the E. scolope squid at levels about equal to the usual symbiotic strain.	complete CACAO 5162

References

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