Chemotactic responses towards various organic compounds mediated by MCP2923 in Comamonas testosteroni CNB-1

Abstract:

[Objective] MCP2923 is a putative of Comamonas testosteroni CNB-1. The objective of this study was to experimentally characterize MCP2923 for chemotactic response.[Methods] Using swimming plate assay, we determined chemotaxis towards 35 aromatic compounds and 9 Tricarboxylic Acid Cycle intermediates. Agrose-in-plug was used to screen aromatic chemoattractants that might bind to MCP2923 directly. To study the ligand of MCP2923, Isothermal Titration Calorimetry experiment was done to 11 chemoattractants.[Results] Swimming plate assay showed that CNB-1 responded to 12 aromatic compounds and 9 Tricarboxylic Acid Cycle intermediates that were defined as strong, medium and weak chemoattractants. Knockout MCP2923 gene reduced chemotactic responses to these chemoattractants. Complemented with MCP2923 gene to CNB-1△20, chemotaxis toward 15 chemoattractants was restored. Deletion of the ligand binding domain of MCP2923, chemotaxis failed to complement. Isothermal Titration Calorimetry experiment showed no response to the tested 11 compounds, including protocatechuic acid and 4-hydroxybenzoic acid.[Conclusion] MCP2923 mediates chemotaxis towards both aromatic compounds and Tricarboxylic Acid Cycle cycle intermediates by CNB-1. The ligand binding domain of MCP2923 is necessary for triggering chemotaxis toward these chemoattractants.