Horseshoe crab acetyl group-recognizing lectins involved in innate immunity are structurally related to fibrinogen
Horseshoe crab acetyl group-recognizing lectins involved in innate immunity are structurally related to fibrinogen
复制标题
DOI：
10.1073/pnas.96.18.10086
复制
发表时间：
1999-08-31
影响因子：
11.1
通讯作者：
Kawabata, S
中科院分区：
文献类型：
--
作者：
Gokudan, S;Muta, T;Kawabata, S
我们对新分离的鲎（Tachypleus tridentatus）血淋巴前血浆凝集素进行了鉴定和克隆，命名为凝集素5A和凝集素5B (TLs-5)， TLs-5能凝集所有类型的人红细胞以及革兰氏阳性和革兰氏阴性细菌。TLs-5特异性识别含乙酰基的物质，包括非碳水化合物；乙酰基是必需的，足以识别。TLs-5增强了马蹄蟹源大防御素的抑菌活性。ls -5的cDNA序列表明，它们由一个短的n端含cys片段和一个c端纤维蛋白原样结构域组成，与哺乳动物纤维蛋白的序列同源性最高（51%）。然而，TLs-5缺乏胶原结构域，这种结构域存在于一种“花束排列”的纤维蛋白和集合体中。电子显微镜显示，ls -5形成两到四叶螺旋桨结构。马蹄蟹具有脊椎动物纤维蛋白原凝血原的独特功能同源物，作为凝血级联的靶蛋白。我们的观察清楚地表明，马蹄蟹的血淋巴中存在与纤维蛋白原相关的分子，它们具有非自我识别的凝集素功能，纤维蛋白原的祖先可能具有非自我识别的蛋白质功能。
We have characterized and cloned newly isolated lectins front hemolymph plasma of the horseshoe crab Tachypleus tridentatus, which we named tachylectins 5A and 5B (TLs-5), TLs-5 agglutinated all types of human erythrocytes and Gram-positive and Gram-negative bacteria. TLs-5 specifically recognize acetyl group-containing substances including noncarbohydrates; the acetyl group is required and is sufficient for recognition. TLs-5 enhanced the antimicrobial activity of a horseshoe crab-derived big defensin. cDNA sequences of TLs-5 indicated that they consist of a short N-terminal Cys-containing segment and a C-terminal fibrinogen-like domain with the highest sequence identity (51%) to that of mammalian ficolins. TLs-5, however, lack the collagenous domain found in a kind of "bouquet arrangement" of ficolins and collectins. Electron microscopy revealed that TLs-5 form two- to four-bladed propeller structures. The horseshoe crab is equipped with a unique functional homologue of vertebrate fibrinogen, coagulogen, as the target protein of the clotting cascade. Our observations clearly show that the horseshoe crab has fibrinogen-related molecules in hemolymph plasma and that they function as nonself-recognizing lectins, An ancestor of fibrinogen may have functioned as a nonself-recognizing protein.