Weis W I, Kahn R, Fourme R, Drickamer K, Hendrickson W A
Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032.
Science. 1991 Dec 13;254(5038):1608-15. doi: 10.1126/science.1721241.
Calcium-dependent (C-type) animal lectins participate in many cell surface recognition events mediated by protein-carbohydrate interactions. The C-type lectin family includes cell adhesion molecules, endocytic receptors, and extracellular matrix proteins. Mammalian mannose-binding proteins are C-type lectins that function in antibody-independent host defense against pathogens. The crystal structure of the carbohydrate-recognition domain of a rat mannose-binding protein, determined as the holmium-substituted complex by multiwavelength anomalous dispersion (MAD) phasing, reveals an unusual fold consisting of two distinct regions, one of which contains extensive nonregular secondary structure stabilized by two holmium ions. The structure explains the conservation of 32 residues in all C-type carbohydrate-recognition domains, suggesting that the fold seen here is common to these domains. The strong anomalous scattering observed at the Ho LIII edge demonstrates that traditional heavy atom complexes will be generally amenable to the MAD phasing method.
钙依赖性（C型）动物凝集素参与许多由蛋白质-碳水化合物相互作用介导的细胞表面识别事件。C型凝集素家族包括细胞粘附分子、内吞受体和细胞外基质蛋白。哺乳动物甘露糖结合蛋白是C型凝集素，在抗体非依赖性宿主抵御病原体的过程中发挥作用。通过多波长反常散射（MAD）相位测定法确定为钬取代复合物的大鼠甘露糖结合蛋白碳水化合物识别结构域的晶体结构，揭示了一种由两个不同区域组成的异常折叠，其中一个区域包含由两个钬离子稳定的广泛不规则二级结构。该结构解释了所有C型碳水化合物识别结构域中32个残基的保守性，表明此处所见的折叠对于这些结构域是常见的。在Ho LIII边缘观察到的强反常散射表明，传统的重原子复合物通常适用于MAD相位测定法。
