From signal perception to signal transduction: ligand‐induced dimeric switch of DctB sensory domain in solution |
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| Authors: | Beiyan Nan Xin Liu Yanfeng Zhou Jiwei Liu Le Zhang Jin Wen Xiaodong Zhang Xiao‐Dong Su Yi‐Ping Wang |
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| Institution: | 1. National Laboratory of Protein Engineering and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing 100871, China.;2. Present address: Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720 USA;3. These authors contribute equally to this work.;4. Immune Disease Institute, Harvard Medical School, Boston, MA 02115 USA.;5. Division of Molecular Biosciences, Imperial College London, London SW7 2AZ, UK. |
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| Abstract: | Sinorhizobium meliloti DctB is a typical transmembrane sensory histidine kinase, which senses C4‐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. |
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