The long-term objective of our research is to define signals that allow bacteria to communicate with a host and to identify the pathways by which they respond to the host environment. The symbiotic association between the Hawaiian squid, Euprymna scolopes, and its bacterial partner, Vibrio fischeri, provides a simple, elegant model system for studying bacteria-animal interactions. Only V.fischeri colonizes the squid. The evidence to date suggests that V.fischeri actively participates in achievingthe observed specificity of the association. The factors that dictate this specificity, however, are not yet understood. We have identified a cluster of genes (syp, symbiosis polysaccharide locus) that is required for V. fischeri to initiate symbiosis, and an unlinked sensor kinase regulator, rscS, that controls syp transcription. Four additional regulators are proposed or known to also control syp transcription, including a a^-dependent response regulator, SypG, and 2 additional 2-component regulators. Thus, syp is controlled by at least 3 proteins that are predicted to sense and respond to the environment. Multi-copy expression of a particular allele (rscS*) causes V.fischeri to express syp-dependent novel phenotypes consistent with altered cell-cell interactions: wrinkled colonies on solid complex media and pellicle formation in liquid minimal medium.Wepropose to elucidate the major regulatory mechanisms controlling syp transcription and identify additional genes associated with syp- dependent phenotypes. We will identify the polysaccharide produced by the syp locus and identify any differences in cell surface properties. Finally, we will examine in more detail the nature of the symbiosis defect of syp mutants and explore possible explanations to account for it. The experiments proposed here will expand our understanding of how colonization is initiated and how signal exchange occurs between a prokaryote and a eukaryote during the establishment of a long-term association. The relevance to public health lies in the potential of this model system to reveal novel mechanisms by which bacteria interact with an animal host. Such information could potentially allow the design of new antimicrobial agents. Our research organism is closely related to bacteria that cause gastroenteritis in humans, includingthe emerging pathogens, V.parahaemolyticus and V. vulnificus. Studying this model may also lead to approaches that prevent, reduce or treat such infections.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
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Prokaryotic Cell and Molecular Biology Study Section (PCMB)
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Anderson, James J
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Loyola University Chicago
Schools of Medicine
United States
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Marsden, Anne E; Grudzinski, Kevin; Ondrey, Jakob M et al. (2017) Impact of Salt and Nutrient Content on Biofilm Formation by Vibrio fischeri. PLoS One 12:e0169521
Singh, Priyanka; Brooks 2nd, John F; Ray, Valerie A et al. (2015) CysK Plays a Role in Biofilm Formation and Colonization by Vibrio fischeri. Appl Environ Microbiol 81:5223-34
Thompson, Cecilia M; Visick, Karen L (2015) Assessing the function of STAS domain protein SypA in Vibrio fischeri using a comparative analysis. Front Microbiol 6:760
Norsworthy, Allison N; Visick, Karen L (2015) Signaling between two interacting sensor kinases promotes biofilms and colonization by a bacterial symbiont. Mol Microbiol 96:233-48
Ray, Valerie A; Driks, Adam; Visick, Karen L (2015) Identification of a novel matrix protein that promotes biofilm maturation in Vibrio fischeri. J Bacteriol 197:518-28
Ondrey, Jakob M; Visick, Karen L (2014) Engineering Vibrio fischeri for Inducible Gene Expression. Open Microbiol J 8:122-9
Miyashiro, Tim; Oehlert, Dane; Ray, Valerie A et al. (2014) The putative oligosaccharide translocase SypK connects biofilm formation with quorum signaling in Vibrio fischeri. Microbiologyopen 3:836-48
Visick, Karen L; Quirke, Kevin P; McEwen, Sheila M (2013) Arabinose induces pellicle formation by Vibrio fischeri. Appl Environ Microbiol 79:2069-80
Norsworthy, Allison N; Visick, Karen L (2013) Gimme shelter: how Vibrio fischeri successfully navigates an animal's multiple environments. Front Microbiol 4:356
Morris, Andrew R; Visick, Karen L (2013) The response regulator SypE controls biofilm formation and colonization through phosphorylation of the syp-encoded regulator SypA in Vibrio fischeri. Mol Microbiol 87:509-25

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