title: Direct sensing and signal transduction during bacterial chemotaxis toward aromatic compounds in Comamonas testosteroni.
abstract: Micro-organisms sense and chemotactically respond to aromatic compounds. Although the existence of chemoreceptors that bind to aromatic attractants and subsequently trigger chemotaxis have long been speculated, such a chemoreceptor has not been demonstrated. In this report, we demonstrated that the chemoreceptor MCP2901 from Comamonas testosteroni CNB-1 binds to aromatic compounds and initiates downstream chemotactic signaling in addition to its ability to trigger chemotaxis via citrate binding. The function of gene MCP2901 was investigated by genetic deletion from CNB-1 and genetic complementation of the methyl-accepting chemotaxis protein (MCP)-null mutant CNB-1Δ20. Results showed that the expression of MCP2901 in the MCP-null mutant restored chemotaxis toward nine tested aromatic compounds and nine carboxylic acids. Isothermal titration calorimetry (ITC) analyses demonstrated that the ligand-binding domain of MCP2901 (MCP2901LBD) bound to citrate, and weakly to gentisate and 4-hydroxybenzoate. Additionally, ITC assays indicated that MCP2901LBD bound strongly to 2,6-dihydroxybenzoate and 2-hydroxybenzoate, which are isomers of gentisate and 4-hydroxybenzoate respectively that are not metabolized by CNB-1. Agarose-in-plug and capillary assays showed that these two molecules serve as chemoattractants for CNB-1. Through constructing membrane-like MCP2901-inserted Nanodiscs and phosphorelay activity assays, we demonstrated that 2,6-dihydroxybenzoate and 2-hydroxybenzoate altered kinase activity of CheA. This is the first evidence of an MCP binding to an aromatic molecule and triggering signal transduction for bacterial chemotaxis.
authors.affiliation: State Key Laboratory of Microbial Resources and Environmental Microbiology Research Center, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China.|University of Chinese Academy of Sciences, Beijing, 100049, China.
authors.forename: Zhou
authors.initials: Z
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Microbial Resources and Environmental Microbiology Research Center, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Ni
authors.affiliation: State Key Laboratory of Microbial Resources and Environmental Microbiology Research Center, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China.|IMCAS-RCEECAS Joint Laboratory for Environmental Microbial Technology, Beijing, China.
authors.forename: Cheng-Ying
authors.initials: CY
authors.lastname: Jiang
authors.affiliation: State Key Laboratory of Microbial Resources and Environmental Microbiology Research Center, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China.|University of Chinese Academy of Sciences, Beijing, 100049, China.
authors.forename: Yu-Fan
authors.initials: YF
authors.lastname: Wu
authors.affiliation: State Key Laboratory of Microbial Resources and Environmental Microbiology Research Center, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China.|University of Chinese Academy of Sciences, Beijing, 100049, China.
authors.forename: Yun-Zhe
authors.initials: YZ
authors.lastname: He
authors.affiliation: Department of Microbiology and Molecular Genetics, University of California, Davis, CA, 95616, USA.
authors.forename: Rebecca E
authors.initials: RE
authors.lastname: Parales
authors.affiliation: State Key Laboratory of Microbial Resources and Environmental Microbiology Research Center, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China.|University of Chinese Academy of Sciences, Beijing, 100049, China.|IMCAS-RCEECAS Joint Laboratory for Environmental Microbial Technology, Beijing, China.
authors.forename: Shuang-Jiang
authors.initials: SJ
authors.lastname: Liu
mesh_terms: D024322:Amino Acids, Aromatic; D001426:Bacterial Proteins / Q000378:metabolism; D002628:Chemoreceptor Cells / Q000378:metabolism*; D002633:Chemotaxis / Q000502:physiology*; D019343:Citric Acid / Q000378:metabolism; D020604:Comamonas testosteroni / Q000378:metabolism*; D017353:Gene Deletion; D005816:Genetic Complementation Test; D062385:Hydroxybenzoates / Q000378:metabolism; D000072236:Methyl-Accepting Chemotaxis Proteins; D011485:Protein Binding; D015398:Signal Transduction / Q000502:physiology
chemical_list: D024322:Amino Acids, Aromatic; D001426:Bacterial Proteins; D062385:Hydroxybenzoates; D000072236:Methyl-Accepting Chemotaxis Proteins; D019343:Citric Acid