title: Non-native acylated homoserine lactones reveal that LuxIR quorum sensing promotes symbiont stability.
abstract: Quorum sensing, a group behaviour coordinated by a diffusible pheromone signal and a cognate receptor, is typical of bacteria that form symbioses with plants and animals. LuxIR-type N-acyl L-homoserine (AHL) quorum sensing is common in Gram-negative Proteobacteria, and many members of this group have additional quorum-sensing networks. The bioluminescent symbiont Vibrio fischeri encodes two AHL signal synthases: AinS and LuxI. AinS-dependent quorum sensing converges with LuxI-dependent quorum sensing at the LuxR regulatory element. Both AinS- and LuxI-mediated signalling are required for efficient and persistent colonization of the squid host, Euprymna scolopes. The basis of the mutualism is symbiont bioluminescence, which is regulated by both LuxI- and AinS-dependent quorum sensing, and is essential for maintaining a colonization of the host. Here, we used chemical and genetic approaches to probe the dynamics of LuxI- and AinS-mediated regulation of bioluminescence during symbiosis. We demonstrate that both native AHLs and non-native AHL analogues can be used to non-invasively and specifically modulate induction of symbiotic bioluminescence via LuxI-dependent quorum sensing. Our data suggest that the first day of colonization, during which symbiont bioluminescence is induced by LuxIR, is a critical period that determines the stability of the V. fischeri population once symbiosis is established.
authors.affiliation: Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, 1550 Linden Drive, Madison WI 53706.
authors.forename: Sarah V
authors.initials: SV
authors.lastname: Studer
authors.affiliation: Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, 1550 Linden Drive, Madison WI 53706.
authors.forename: Julia A
authors.initials: JA
authors.lastname: Schwartzman
authors.affiliation: Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, 1550 Linden Drive, Madison WI 53706.
authors.forename: Jessica S
authors.initials: JS
authors.lastname: Ho
authors.affiliation: Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison WI 53706.
authors.forename: Grant D
authors.initials: GD
authors.lastname: Geske
authors.affiliation: Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison WI 53706.
authors.forename: Helen E
authors.initials: HE
authors.lastname: Blackwell
authors.affiliation: Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, 1550 Linden Drive, Madison WI 53706.
authors.forename: Edward G
authors.initials: EG
authors.lastname: Ruby
mesh_terms: D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000378:metabolism; D048908:Aliivibrio fischeri / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D049832:Decapodiformes / Q000382:microbiology; D015964:Gene Expression Regulation, Bacterial; D049449:Luminescence; D053038:Quorum Sensing / Q000235:genetics*; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism; D013559:Symbiosis / Q000235:genetics*; D013997:Time Factors; D015534:Trans-Activators / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
chemical_list: C096878:AinS protein, Vibrio fischeri; D001426:Bacterial Proteins; C085427:LuxI protein, Bacteria; D012097:Repressor Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C064778:LuxR autoinducer binding proteins; C088386:homoserine lactone; D015107:4-Butyrolactone