6D8V

Methyl-accepting Chemotaxis protein X

6D8V の概要

• エントリーDOI: 10.2210/pdb6d8v/pdb
• 分子名称: Probable chemoreceptor (Methyl-accepting chemotaxis) transmembrane protein, 2-AMINO-2-HYDROXYMETHYL-PROPANE-1,3-DIOL, 1,1-DIMETHYL-PROLINIUM, ... (4 entities in total)
• 機能のキーワード: mcp, chemotaxis, membrane protein
• 由来する生物種: Rhizobium meliloti (strain 1021) (Ensifer meliloti)
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 28984.43

構造登録者

Shrestha, M.,Schubot, F.D. (登録日: 2018-04-27, 公開日: 2019-04-17, 最終更新日: 2024-03-13)

主引用文献

Shrestha, M.,Compton, K.K.,Mancl, J.M.,Webb, B.A.,Brown, A.M.,Scharf, B.E.,Schubot, F.D.
Structure of the sensory domain of McpX fromSinorhizobium meliloti, the first known bacterial chemotactic sensor for quaternary ammonium compounds.
Biochem. J., 475:3949-3962, 2018

PubMed Abstract: The α-proteobacterium can live freely in the soil or engage in a symbiosis with its legume host. facilitates nitrogen fixation in root nodules, thus providing pivotal, utilizable nitrogen to the host. The organism has eight chemoreceptors, namely McpT to McpZ and IcpA that facilitate chemotaxis. McpX is the first known bacterial sensor of quaternary ammonium compounds (QACs) such as choline and betaines. Because QACs are exuded at chemotaxis-relevant concentrations by germinating alfalfa seeds, McpX has been proposed to contribute to host-specific chemotaxis. We have determined the crystal structure of the McpX periplasmic region (McpX) in complex with the proline betaine at 2.7 Å resolution. In the crystal, the protein forms a symmetric dimer with one proline betaine molecule bound to each monomer of McpX within membrane-distal CACHE module. The ligand is bound through cation-πinteractions with four aromatic amino acid residues. Mutational analysis in conjunction with binding studies revealed that a conserved aspartate residue is pivotal for ligand binding. We discovered that, in a striking example of convergent evolution, the ligand-binding site of McpX resembles that of a group of structurally unrelated betaine-binding proteins including ProX and OpuAC. Through this comparison and docking studies, we rationalized the specificity of McpX for this specific group of ligands. Collectively, our structural, biochemical, and molecular docking data have revealed the molecular determinants in McpX that are crucial for its rare ligand specificity for QACs.

PubMed: 30442721
DOI: 10.1042/BCJ20180769

実験手法

X-RAY DIFFRACTION (2.8 Å)