BioMol-Lab, Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Ceará, P. O. Box 6043, 60.455-970 Fortaleza, Ceará, Brazil.
Biochimie. 2011 May;93(5):806-16. doi: 10.1016/j.biochi.2011.01.006. Epub 2011 Jan 26.
Legume lectins, despite high sequence homology, express diverse biological activities that vary in potency and efficacy. In studies reported here, the mannose-specific lectin from Cymbosema roseum (CRLI), which binds N-glycoproteins, shows both pro-inflammatory effects when administered by local injection and anti-inflammatory effects when by systemic injection. Protein sequencing was obtained by Tandem Mass Spectrometry and the crystal structure was solved by X-ray crystallography using a Synchrotron radiation source. Molecular replacement and refinement were performed using CCP4 and the carbohydrate binding properties were described by affinity assays and computational docking. Biological assays were performed in order to evaluate the lectin edematogenic activity. The crystal structure of CRLI was established to a 1.8Å resolution in order to determine a structural basis for these differing activities. The structure of CRLI is closely homologous to those of other legume lectins at the monomer level and assembles into tetramers as do many of its homologues. The CRLI carbohydrate binding site was predicted by docking with a specific inhibitory trisaccharide. CRLI possesses a hydrophobic pocket for the binding of α-aminobutyric acid and that pocket is occupied in this structure as are the binding sites for calcium and manganese cations characteristic of legume lectins. CRLI route-dependent effects for acute inflammation are related to its carbohydrate binding domain (due to inhibition caused by the presence of α-methyl-mannoside), and are based on comparative analysis with ConA crystal structure. This may be due to carbohydrate binding site design, which differs at Tyr12 and Glu205 position.
豆科植物凝集素，尽管具有高度的序列同源性，但表达的生物学活性却多种多样，在效力和功效上有所不同。在本报告的研究中，从 Cymbosema roseum（CRLI）中分离出的甘露糖特异性凝集素（CRLI），当通过局部注射给药时表现出促炎作用，而当通过全身注射给药时则表现出抗炎作用。通过串联质谱法获得蛋白质测序，使用同步辐射源通过 X 射线晶体学解决晶体结构。使用 CCP4 进行分子替换和细化，通过亲和测定和计算对接描述碳水化合物结合特性。进行生物测定以评估凝集素的水肿活性。为了确定这些不同活性的结构基础，建立了 CRLI 的晶体结构，分辨率为 1.8Å。CRLI 的结构在单体水平上与其他豆科植物凝集素密切同源，并像许多同源物一样组装成四聚体。通过与特定的抑制性三糖对接预测了 CRLI 的碳水化合物结合位点。CRLI 具有一个用于结合α-氨基丁酸的疏水口袋，并且在该结构中占据该口袋，以及结合α-甲基甘露糖苷存在时引起抑制的特性，是豆科植物凝集素的特征。CRLI 急性炎症的依赖途径效应与其碳水化合物结合结构域有关（由于α-甲基甘露糖苷的存在引起的抑制），并基于与 ConA 晶体结构的比较分析。这可能是由于碳水化合物结合位点设计在 Tyr12 和 Glu205 位置的差异。
