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From signal perception to signal transduction: ligand‐induced dimeric switch of DctB sensory domain in solution
Author(s) -
Nan Beiyan,
Liu Xin,
Zhou Yanfeng,
Liu Jiwei,
Zhang Le,
Wen Jin,
Zhang Xiaodong,
Su XiaoDong,
Wang YiPing
Publication year - 2010
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/j.1365-2958.2010.07069.x
Subject(s) - periplasmic space , ligand (biochemistry) , histidine kinase , biology , signal transduction , autophosphorylation , transmembrane protein , biochemistry , conformational change , mutagenesis , receptor , microbiology and biotechnology , biophysics , histidine , phosphorylation , mutation , amino acid , gene , protein kinase a , escherichia coli
Summary Sinorhizobium meliloti DctB is a typical transmembrane sensory histidine kinase, which senses C 4 ‐dicarboxylic acids (DCA) and regulates the expression of DctA, the DCA transporter. We previously reported the crystal structures of its periplasmic sensory domain (DctBp) in apo and succinate‐bound states, and these structures showed dramatic conformational changes at dimeric level. Here we show a ligand‐induced dimeric switch in solution and a strong correlation between DctBp's dimerization states and the in vivo activities of DctB. Using site‐directed mutagenesis, we identify important determinants for signal perception and transduction. Specifically, we show that the ligand‐binding pocket is essential for DCA‐induced ‘on’ activity of DctB. Mutations at different sections of DctBp's dimerization interface can lock full‐length DctB at either ‘on’ or ‘off’ state, independent of ligand binding. Taken together, these results suggest that DctBp's signal perception and transduction occur through a ‘ligand‐induced dimeric switch’, in which the changes in the dimeric conformations upon ligand binding are responsible for the signal transduction in DctB.