Abhinav K V, Sharma Kaushal, Surolia Avadhesha, Vijayan Mamannamana
Molecular Biophysics Unit, Indian Institute of Science, Bangalore, Karnataka, 560012, India.
IUBMB Life. 2016 Dec;68(12):971-979. doi: 10.1002/iub.1572. Epub 2016 Nov 3.
The crystal structures of jacalin complexed with Gal α-(1,4) Gal and Gal α-(1,3) Gal β-(1,4) Gal have been determined with the primary objective of exploring the effect of linkage on the location of reducing and non-reducing sugars in the extended binding site of the lectin, an issue which has not been studied thoroughly. Contrary to the earlier surmise based on simple steric considerations, the two structures demonstrate that α-linked sugars can bind to jacalin with nonreducing sugar at the primary binding site. This is made possible substantially on account of the hitherto underestimated plasticity of a non-polar region of the extended binding site. Modeling studies involving conformational search and energy minimization, along with available crystallographic and thermodynamic data, indicate a strong preference for complexation with Gal β-(1,3) Gal with the reducing Gal at the primary site, followed by that with Gal α-(1,3) Gal, with the reducing or non-reducing Gal located at the primary binding site. This observation is in consonance with the facility of jacalin to bind mucin type O-glycans containing T-antigen core. © 2016 IUBMB Life, 68(12):971-979, 2016.
已确定了与Galα-(1,4)Gal和Galα-(1,3)Galβ-(1,4)Gal复合的jacalin的晶体结构，其主要目的是探索连接方式对凝集素扩展结合位点中还原糖和非还原糖位置的影响，这一问题尚未得到充分研究。与基于简单空间位阻考虑的早期推测相反，这两种结构表明α连接的糖可以在主要结合位点以非还原糖与jacalin结合。这在很大程度上是由于扩展结合位点非极性区域迄今被低估的可塑性。涉及构象搜索和能量最小化的建模研究，以及现有的晶体学和热力学数据表明，与Galβ-(1,3)Gal复合时强烈倾向于在主要位点以还原型Gal结合，其次是与Galα-(1,3)Gal复合，还原型或非还原型Gal位于主要结合位点。这一观察结果与jacalin结合含T抗原核心的粘蛋白型O-聚糖的能力一致。©2016国际生物化学与分子生物学联盟生命科学部，68(12):971 - 979，2016年。
