ligand-binding sensor domain of Comamonas testosteroni CNB-2 MCP2201 and similar chemoreceptors
This family includes the ligand-binding sensor domain of Comamonas testosteroni transmembrane chemoreceptor CNB-2 MCP2201 and similar chemoreceptors. The C. testosteroni methyl-accepting chemotaxis protein MCP2201 triggers chemotaxis towards tricarboxylic acid cycle intermediates such as citric acid and aromatic compounds. While the apo-form ligand binding domain (LBD) forms a typical four-helix bundle homodimer, similar to other chemoreceptors in the superfamily such as Escherichia coli Tar and Tsr, the citrate-bound LBD reveals a four-helix bundle homotrimer. This type of oligomerization has never been observed in other bacterial chemoreceptor LBD. Site-directed mutations of key amino acid residues have demonstrated the physiological importance of the homotrimer for chemotaxis.
Jiyao W et al.(2023). "The conserved domain database in 2023.",