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Determinants governing ligand specificity of the V ibrio harveyi L ux N quorum‐sensing receptor
Author(s) -
Ke Xiaobo,
Miller Laura C.,
Bassler Bonnie L.
Publication year - 2015
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.12852
Subject(s) - quorum sensing , biology , receptor , microbiology and biotechnology , ligand (biochemistry) , vibrio harveyi , computational biology , bacteria , biochemistry , virulence , genetics , gene , vibrio
Summary 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 V ibrio harveyi exclusively detects the autoinducer N ‐(( R )‐3‐hydroxybutanoyl)‐ L ‐homoserine lactone (3 OH ‐ C 4 HSL ) via the two‐component receptor L ux N . To discover the principles underlying the exquisite selectivity L ux N has for its ligand, we identified L ux N mutants with altered specificity. L ux N uses three mechanisms to verify that the bound molecule is the correct ligand: in the context of the overall ligand‐binding site, H is210 validates the C 3 modification, L eu166 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 L ux N kinase on and kinase off states underpin whether a ligand will act as an antagonist or an agonist. Mutations that bias L ux N to the agonized, kinase off, 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.