Programa de Doctorado en Ciencias Biológicas de la Universidad Autónoma Metropolitana, Apdo Postal 23-181, México, DF 04960, Mexico.
Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Apdo 14-740, México DF 07000, Mexico.
Microbiology (Reading). 2011 Jan;157(Pt 1):209-219. doi: 10.1099/mic.0.040063-0. Epub 2010 Sep 16.
Transferrin (Tf) is a host glycoprotein capable of binding two ferric-iron ions to become holotransferrin (holoTf), which transports iron in to all cells. Entamoeba histolytica is a parasitic protozoan able to use holoTf as a sole iron source in vitro. The mechanism by which this parasite scavenges iron from holoTf is unknown. An E. histolytica holoTf-binding protein (EhTfbp) was purified by using an anti-human transferrin receptor (TfR) monoclonal antibody. EhTfbp was identified by MS/MS analysis and database searches as E. histolytica acetaldehyde/alcohol dehydrogenase-2 (EhADH2), an iron-dependent enzyme. Both EhTfbp and EhADH2 bound holoTf and were recognized by the anti-human TfR antibody, indicating that they correspond to the same protein. It was found that the amoebae internalized holoTf through clathrin-coated pits, suggesting that holoTf endocytosis could be important for the parasite during colonization and invasion of the intestinal mucosa and liver.
转铁蛋白（Tf）是一种宿主糖蛋白，能够结合两个三价铁离子成为全转铁蛋白（holoTf），从而将铁运送到所有细胞中。溶组织内阿米巴原虫是一种寄生的原生动物，能够在体外将 holoTf 作为唯一的铁源。这种寄生虫从 holoTf 中摄取铁的机制尚不清楚。我们使用抗人转铁蛋白受体（TfR）单克隆抗体纯化了溶组织内阿米巴原虫 holoTf 结合蛋白（EhTfbp）。通过 MS/MS 分析和数据库搜索，EhTfbp 被鉴定为溶组织内阿米巴原虫乙醛/乙醇脱氢酶-2（EhADH2），这是一种依赖于铁的酶。EhTfbp 和 EhADH2 都与 holoTf 结合，并被抗人 TfR 抗体识别，这表明它们对应于相同的蛋白。研究发现，阿米巴虫通过网格蛋白包被的陷窝内化 holoTf，这表明 holoTf 的内吞作用对于寄生虫在肠道黏膜和肝脏的定植和侵袭过程中可能很重要。
