Pleurotus ostreatus Lectin (POL) is a 353 amino acid chain lectin that can be purified from the fruiting bodies of the very well-known and widely diffused edible oyster mushrooms (P. ostreatus). The lectin has been partially characterized by different groups and, although it was crystallized about 20 years ago, its 3D structure and the details of its interactions with carbohydrates are still unknown. This paper reports the 3D structure and ligand-binding properties of POL. We have determined the X-ray structure of the apo-protein purified from the fruiting bodies of the mushroom and that of the recombinant protein in complex with melibiose to a resolution of about 2 Å. The lectin is a homodimer in which the two polypeptide chains are linked by a disulfide bridge. A POL monomer is composed of two highly homologous β-jellyroll domains each of which containing a calcium-dependent carbohydrate-binding site. A high degree of sequence similarity is observed between the two carbohydrate-binding modules present in each monomer. The structure of the lectin in complex with melibiose reveals that a POL dimer has four calcium-dependent carbohydrate-binding sites. The interaction with sugars in solution has been characterized by isothermal titration calorimetry and saturation transfer difference NMR and it sheds new light on the molecular determinants of POL specificity. The lectin exhibits in vitro antiproliferative effects against human cancer cell lines and presents structural similarity with the prototype member of the CBM67 family, the noncatalytic domain of Streptomyces avermitilis α-rhamnosidase.

中文翻译：

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平菇（Pleurotus ostreatus）凝集素的结构和特性。

Pleurotus ostreatus凝集素 (POL) 是一种 353 个氨基酸链的凝集素，可从广为人知且广泛分布的食用平菇 ( P. ostreatus)的子实体中纯化）。凝集素的部分特征被不同的群体所表征，尽管它在大约 20 年前结晶，但其 3D 结构及其与碳水化合物相互作用的细节仍然未知。本文报告了 POL 的 3D 结构和配体结合特性。我们已经确定了从蘑菇子实体中纯化的载脂蛋白的 X 射线结构，以及与蜜二糖复合的重组蛋白的 X 射线结构，分辨率约为 2 Å。凝集素是一种同源二聚体，其中两条多肽链通过二硫键连接。POL 单体由两个高度同源的 β-jellyroll 结构域组成，每个结构域都包含一个钙依赖性碳水化合物结合位点。在每个单体中存在的两个碳水化合物结合模块之间观察到高度的序列相似性。凝集素与蜜二糖复合物的结构表明 POL 二聚体具有四个钙依赖性碳水化合物结合位点。与溶液中糖类的相互作用已通过等温滴定量热法和饱和转移差异核磁共振进行表征，它为 POL 特异性的分子决定因素提供了新的线索。凝集素对人类癌细胞系表现出体外抗增殖作用，并与 CBM67 家族的原型成员（其非催化结构域）具有结构相似性。与溶液中糖类的相互作用已通过等温滴定量热法和饱和转移差异核磁共振进行表征，它为 POL 特异性的分子决定因素提供了新的线索。凝集素对人类癌细胞系表现出体外抗增殖作用，并与 CBM67 家族的原型成员（其非催化结构域）具有结构相似性。与溶液中糖类的相互作用已通过等温滴定量热法和饱和转移差异核磁共振进行表征，它为 POL 特异性的分子决定因素提供了新的线索。凝集素对人类癌细胞系表现出体外抗增殖作用，并与 CBM67 家族的原型成员（其非催化结构域）具有结构相似性。阿维链霉菌α-鼠李糖苷酶。