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Determinants governing ligand specificity of the V ibrio harveyi LuxN quorum-sensing receptor

Author(s): Ke, Xiaobo; Miller, Laura C; Bassler, Bonnie L

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Abstract: Quorum sensing is a process of bacterial cell-cell communication that relies on the production, release, and receptor-driven detection of extracellular signal molecules called autoinducers. The quorum-sensing bacterium Vibrio harveyi exclusively detects the autoinducer N-((R)-3-hydroxybutanoyl)-L-homoserine lactone (3OH-C4 HSL) via the two-component receptor LuxN. To discover the principles underlying the exquisite selectivity LuxN has for its ligand, we identified LuxN mutants with altered specificity. LuxN uses three mechanisms to verify that the bound molecule is the correct ligand: In the context of the overall ligand-binding site, His210 validates the C3 modification, Leu166 surveys the chain-length, and a strong steady-state kinase bias imposes an energetic hurdle for inappropriate ligands to elicit signal transduction. Affinities for the LuxN Kinaseon and Kinaseoff states underpin whether a ligand will act as an antagonist or an agonist. Mutations that bias LuxN to the agonized, Kinaseoff, state are clustered in a region adjacent to the ligand-binding site, suggesting that this region acts as the switch that triggers signal transduction. Together, our analyses illuminate how a histidine sensor kinase differentiates between ligands and exploits those differences to regulate its signaling activity.
Publication Date: Jan-2015
Electronic Publication Date: 27-Nov-2014
Citation: Ke, Xiaobo, Miller, Laura C, Bassler, Bonnie L. (2015). Determinants governing ligand specificity of the V ibrio harveyi LuxN quorum-sensing receptor. Molecular Microbiology, 95 (1), 127 - 142. doi:10.1111/mmi.12852
DOI: doi:10.1111/mmi.12852
ISSN: 0950-382X
Pages: 1 - 25
Type of Material: Journal Article
Journal/Proceeding Title: Molecular Microbiology
Version: Author's manuscript

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