Antonik Paweł M, Volkov Alexander N, Broder Ursula N, Re Daniele Lo, van Nuland Nico A J, Crowley Peter B
School of Chemistry, National University of Ireland Galway , University Road, Galway, Ireland.
Department of Food BioSciences, Teagasc Food Research Centre , Ashtown, Dublin 15, Ireland.
Biochemistry. 2016 Mar 1;55(8):1195-203. doi: 10.1021/acs.biochem.5b01212. Epub 2016 Feb 16.
Sugar binding by a cell surface ∼29 kDa lectin (RSL) from the bacterium Ralstonia solanacearum was characterized by NMR spectroscopy. The complexes formed with four monosaccharides and four fucosides were studied. Complete resonance assignments and backbone dynamics were determined for RSL in the sugar-free form and when bound to l-fucose or d-mannose. RSL was found to interact with both the α- and the β-anomer of l-fucose and the "fucose like" sugars d-arabinose and l-galactose. Peak splitting was observed for some resonances of the binding site residues. The assignment of the split signals to the α- or β-anomer was confirmed by comparison with the spectra of RSL bound to methyl-α-l-fucoside or methyl-β-l-fucoside. The backbone dynamics of RSL were sensitive to the presence of ligand, with the protein adopting a more compact structure upon binding to l-fucose. Taking advantage of tryptophan residues in the binding sites, we show that the indole resonance is an excellent reporter on ligand binding. Each sugar resulted in a distinct signature of chemical shift perturbations, suggesting that tryptophan signals are a sufficient probe of sugar binding.
通过核磁共振光谱对来自青枯雷尔氏菌的一种细胞表面约29 kDa凝集素（RSL）与糖的结合进行了表征。研究了与四种单糖和四种岩藻糖苷形成的复合物。确定了无糖形式的RSL以及与L-岩藻糖或D-甘露糖结合时的完整共振归属和主链动力学。发现RSL与L-岩藻糖的α-和β-异头物以及“类岩藻糖”糖D-阿拉伯糖和L-半乳糖相互作用。观察到结合位点残基的一些共振峰发生分裂。通过与结合甲基-α-L-岩藻糖苷或甲基-β-L-岩藻糖苷的RSL光谱进行比较，证实了分裂信号对α-或β-异头物的归属。RSL的主链动力学对配体的存在敏感，与L-岩藻糖结合时蛋白质采用更紧凑的结构。利用结合位点中的色氨酸残基，我们表明吲哚共振是配体结合的极佳报告基团。每种糖都导致化学位移扰动的独特特征，表明色氨酸信号是糖结合的充分探针。
