Austrian Centre of Industrial Biotechnology , Petersgasse 14 , 8010 Graz , Austria.
Institute of Molecular Biotechnology , Graz University of Technology , Petersgasse 14 , 8010 Graz , Austria.
ACS Chem Biol. 2018 Aug 17;13(8):2211-2219. doi: 10.1021/acschembio.8b00377. Epub 2018 Jun 12.
Protein-carbohydrate interactions play crucial roles in biology. Understanding and modifying these interactions is of major interest for fighting many diseases. We took a synthetic biology approach and incorporated noncanonical amino acids into a bacterial lectin to modulate its interactions with carbohydrates. We focused on tryptophan, which is prevalent in carbohydrate binding sites. The exchange of the tryptophan residues with analogs fluorinated at different positions resulted in three distinctly fluorinated variants of the lectin from Ralstonia solanacearum. We observed differences in stability and affinity toward fucosylated glycans and rationalized them by X-ray and modeling studies. While fluorination decreased the aromaticity of the indole ring and, therefore, the strength of carbohydrate-aromatic interactions, additional weak hydrogen bonds were formed between fluorine and the ligand hydroxyl groups. Our approach opens new possibilities to engineer carbohydrate receptors.
蛋白质-碳水化合物相互作用在生物学中起着至关重要的作用。了解和修饰这些相互作用对于对抗许多疾病具有重要意义。我们采用合成生物学的方法，将非天然氨基酸引入到细菌凝集素中，以调节其与碳水化合物的相互作用。我们专注于色氨酸，它在碳水化合物结合位点中很常见。用在不同位置氟化的类似物替换色氨酸残基，导致罗尔斯通氏菌的凝集素产生三个明显不同的氟化变体。我们观察到了它们在稳定性和对岩藻糖基化糖的亲和力方面的差异，并通过 X 射线和建模研究对其进行了合理化解释。虽然氟化降低了吲哚环的芳香性，从而降低了碳水化合物-芳香族相互作用的强度，但在氟原子和配体羟基之间形成了额外的弱氢键。我们的方法为工程化碳水化合物受体开辟了新的可能性。
