The epithelial adhesin 1 (Epa1p) from the human-pathogenic yeast Candida glabrata: structural and functional study of the carbohydrate-binding domain
The epithelial adhesin 1 (Epa1p) from the human-pathogenic yeast Candida glabrata: structural and functional study of the carbohydrate-binding domain
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DOI：
10.1107/s0907444911054898
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发表时间：
2012-03-01
影响因子：
2.2
通讯作者：
Willaert, Ronnie G.
中科院分区：
文献类型：
--
作者：
Ielasi, Francesco S.;Decanniere, Klaas;Willaert, Ronnie G.
光滑念珠菌是世界上临床念珠菌病病例的第二大原因。这种机会性病原体粘附人类上皮细胞和内皮细胞的能力依赖于 Epa 粘附素，这是一组细胞壁蛋白，其 N 末端结构域被赋予钙依赖性凝集素活性。这一特征允许酵母细胞通过与细胞膜上表达的聚糖建立多重相互作用来粘附宿主细胞。 Epa1p 粘附素的配体结合结构域是 Epa 家族中特征最明确的结构域之一，在大肠杆菌中表达、纯化并与乳糖形成复合物结晶。利用与另一种酵母粘附素（来自酿酒酵母的 Flo5p 絮凝蛋白）的结构域的序列同一性进行分子替换，并以 1.65 埃的分辨率解析了该结构域的结构。该蛋白质是 PA14 超家族的成员。它具有 β 夹心核心和 DcisD 钙结合基序，该基序也存在于 Flo5p 的结合位点中。然而，Epa1p 与该同源物的不同之处在于缺乏 Flo5 样子结构域，并且溶剂对结合位点的可及性显着降低，其中钙离子在与碳水化合物的相互作用中仍然发挥着积极的作用。这种结构见解与荧光分析数据一起证实并解释了与酿酒酵母絮凝蛋白相比，Epa1p 粘附素对聚糖分子具有更高的特异性。
The yeast Candida glabrata represents the second major cause of clinical candidiasis cases in the world. The ability of this opportunistic pathogen to adhere to human epithelial and endothelial cells relies on the Epa adhesins, a large set of cellwall proteins whose N-terminal domains are endowed with a calcium-dependent lectin activity. This feature allows the yeast cells to adhere to host cells by establishing multiple interactions with the glycans expressed on their cell membrane. The ligand-binding domain of the Epa1p adhesin, which is one of the best characterized in the Epa family, was expressed in Escherichia coli, purified and crystallized in complex with lactose. Sequence identity with the domain of another yeast adhesin, the Flo5p flocculin from Saccharomyces cerevisiae, was exploited for molecular replacement and the structure of the domain was solved at a resolution of 1.65 angstrom. The protein is a member of the PA14 superfamily. It has a beta-sandwich core and a DcisD calcium-binding motif, which is also present in the binding site of Flo5p. However, Epa1p differs from this homologue by the lack of a Flo5-like subdomain and by a significantly decreased accessibility of the solvent to the binding site, in which a calcium ion still plays an active role in the interactions with carbohydrates. This structural insight, together with fluorescence-assay data, confirms and explains the higher specificity of Epa1p adhesin for glycan molecules compared with the S. cerevisiae flocculins.