Toxoplasma gondii micronemal protein MIC1 is a lactose-binding lectin
Toxoplasma gondii micronemal protein MIC1 is a lactose-binding lectin
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DOI：
10.1093/glycob/11.7.541
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发表时间：
2001-07-01
期刊：
影响因子：
4.3
通讯作者：
Panunto-Castelo, A
中科院分区：
文献类型：
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作者：
Lourenço, EV;Pereira, SR;Panunto-Castelo, A
弓形虫侵入宿主细胞是一个多步骤的过程，其中第一步是顶端释放与宿主受体相互作用的微线蛋白。我们证明了微线蛋白1（micronemal protein 1，MIC 1）是一种乳糖结合凝集素，MIC 1和MIC 4在RH株速殖子可溶性抗原组分的乳糖洗脱（Lac（+））组分中被回收，MIC 1和MIC 4均通过N-末端微测序鉴定。MIC 4也通过测序从表达文库中分离的cDNA克隆来鉴定，所述表达文库在用小鼠多克隆抗60/70 kDa（Lac（+）蛋白）血清筛选后分离。该抗血清经激光共聚焦显微镜观察，将Lac（+）蛋白定位于弓形虫速殖子顶端区，Lac（+）组分诱导血凝（主要是A型人红细胞），可被β-半乳糖苷抑制（3 mM乳糖和12 mM半乳糖），但不超过100 mM蜜二糖（α-半乳糖苷）、岩藻糖、甘露糖或葡萄糖或0.2mg/ml肝素。Lac（+）制剂的凝集素活性归因于MIC 1，因为印迹的MIC 1而非天然MIC 4结合人A型红细胞和胎球蛋白，MIC 1和MIC 4的共纯化可能是由于它们的关联，如其他人所报告的。这些数据表明，MIC 1可能通过其凝集素活性在弓形虫感染中起作用。
Host cell invasion by Toxoplasma gondii is a multistep process with one of the first steps being the apical release of micronemal proteins that interact with host receptors. We demonstrate here that micronemal protein 1 (MIC1) is a lactose-binding lectin, MIC1 and MIC4 were recovered in the lactose-eluted (Lac(+)) fraction on affinity chromatography on immobilized lactose of the soluble antigen fraction from tachyzoites of the virulent RH strain, MIC1 and MIC4 were both identified by N-terminal microsequencing. MIC4 was also identified by sequencing cDNA clones isolated from an expression library following screening with mouse polyclonal anti-60/70 kDa (Lac(+) proteins) serum. This antiserum localized the Lac(+) proteins on the apical region of T, gondii tachyzoites by confocal microscopy, The Lac(+) fraction induced hemagglutination (mainly type A human erythrocytes), which was inhibited by beta -galactosides (3 mM lactose and 12 mM galactose) but not by up to 100 mM melibiose (alpha -galactoside), fucose, mannose, or glucose or 0.2 mg/ml heparin, The lectin activity of the Lac(+) preparation was attributed to MIC1, because blotted MIC1, but not native MIC4, bound human erythrocyte type A and fetuin, The copurification of MIC1 and MIC4 may have been due to their association, as reported by others. These data suggest that MIC1 may act through its lectin activity during T, gondii infection.