CGL1 is a mannose-specific lectin isolated from the Pacific oyster Crassostrea gigas, and it belongs to the DM9 domain protein family. Each subunit of the CGL1 dimer consists of a tandem repeat of DM9 motifs, which were originally found in the Drosophila melanogaster genome. The CGL1 protomer contains two carbohydrate-binding sites: a high-affinity site A and a low-affinity site B. An assay using dendrimers containing oligomannose from yeast (Saccharomyces cerevisiae) revealed that CGL1 exhibited significantly higher affinity for mannotetraose (Man4) compared to mannobiose (Man2) and mannotriose (Man3). To investigate its oligomannose recognition mechanism, X-ray crystallographic analyses of CGL1/oligomannose complexes were performed. In the CGL1/Man2 and CGL1/Man3 complexes, Manα1-2Man and Manα1-2Manα1-2Man, respectively, were primarily bound to site A, interacting with the non-reducing mannose residue. On the other hand, in the CGL1/Man4 crystal, Man4 (Manα1-2Manα1-2Manα1-6Man) was bound at both site A and site B at the non-reducing and reducing ends, thus linking adjacent CGL1 molecules with crystallographic symmetry. These findings suggest that CGL1 can recognize both the non-reducing and reducing mannose residues of mannose oligosaccharides at its two distinct carbohydrate-binding sites. This enables efficient complex formation, making CGL1 a pattern recognition molecule capable of recognizing diverse structures of mannose-containing carbohydrate chains.

中文翻译：

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X 射线晶体分析揭示了甘露糖寡糖对 CGL1 的识别，CGL1 是一种甘露糖特异性凝集素，含有来自巨牡蛎的 DM9 基序。

CGL1 是从太平洋牡蛎巨牡蛎中分离出来的甘露糖特异性凝集素，属于 DM9 结构域蛋白家族。CGL1 二聚体的每个亚基均由 DM9 基序的串联重复组成，这些基序最初在果蝇基因组中发现。CGL1 原聚体包含两个碳水化合物结合位点：高亲和力位点 A 和低亲和力位点 B。使用含有来自酵母（酿酒酵母）的低聚甘露糖的树枝状聚合物进行的测定表明，与相比，CGL1 对甘露四糖 (Man4) 的亲和力显着更高甘露二糖 (Man2) 和甘露三糖 (Man3)。为了研究其低聚甘露糖识别机制，对 CGL1/低聚甘露糖复合物进行了 X 射线晶体学分析。在CGL1/Man2和CGL1/Man3复合物中，Manα1-2Man和Manα1-2Manα1-2Man分别主要结合至位点A，与非还原性甘露糖残基相互作用。另一方面，在CGL1/Man4晶体中，Man4（Manα1-2Manα1-2Manα1-6Man）在非还原端和还原端的A位点和B位点结合，从而以晶体学对称性连接相邻的CGL1分子。这些发现表明，CGL1 可以在其两个不同的碳水化合物结合位点识别甘露糖寡糖的非还原性和还原性甘露糖残基。这使得复合物的有效形成成为可能，使 CGL1 成为能够识别含甘露糖碳水化合物链的多种结构的模式识别分子。