Zhang L, Leggatt G R, Kalinna B H, Piva T J, McManus D P
Molecular Parasitology Unit, Australian Centre for International and Tropical Health and Nutrition, Bancroft Centre, Brisbane QLD, Australia.
Mol Biochem Parasitol. 1997 Aug;87(2):183-92. doi: 10.1016/s0166-6851(97)00066-2.
We have isolated a cDNA from the hydatid tapeworm, Echinococcus granulosus, encoding a protein that binds laminin. This is the first report of a helminth parasite laminin-binding protein and the first description of a cDNA encoding a laminin-binding protein from a parasite. The cDNA clone (egmo3) was isolated from an E. granulosus protoscolex cDNA expression library, and identified on the basis of sequence homology to the nonintegrin mammalian metastasis-associated 67-kDa laminin receptor (67-LR). The amino acid sequence predicted from the cDNA sequence is 268 residues long with a calculated molecular mass of 29.9 kDa. Southern blot analysis suggested that many copies of the gene may occur in the E. granulosus genome. A Northern blot revealed that the gene is expressed as a single transcript of approximately 1 kb consistent with the size of the cDNA insert. Antibodies raised to the purified protein interacted with a 30 kDa protein in whole E. granulosus protoscoleces. A Western blot of the purified and refolded recombinant protein specifically bound 125I-labelled laminin, as did a synthetic peptide derived from the inferred amino acid sequence of egmo3 which is similar in homology to peptide G, the active ligand-binding site of 67-LR. We also isolated the 3' end of the cDNA encoding the homologous protein from the closely related species, E. multilocularis. The polypeptide encoded by egmo3 also shares substantial identity with the acidic class of ribosomal proteins which are involved in protein synthesis. As such, the egmo3 protein may be multifunctional in E. granulosus, acting as a laminin-binding molecule but also playing a role in cell division and growth.
我们从细粒棘球绦虫中分离出一个编码与层粘连蛋白结合的蛋白质的cDNA。这是关于蠕虫寄生虫层粘连蛋白结合蛋白的首次报道，也是关于寄生虫编码层粘连蛋白结合蛋白的cDNA的首次描述。cDNA克隆（egmo3）是从细粒棘球绦虫原头蚴cDNA表达文库中分离出来的，并根据与非整合素哺乳动物转移相关的67 kDa层粘连蛋白受体（67-LR）的序列同源性进行鉴定。从cDNA序列预测的氨基酸序列长268个残基，计算分子量为29.9 kDa。Southern印迹分析表明，该基因在细粒棘球绦虫基因组中可能有多个拷贝。Northern印迹显示该基因表达为一个约1 kb的单一转录本，与cDNA插入片段的大小一致。针对纯化蛋白产生的抗体与整个细粒棘球绦虫原头蚴中的一种30 kDa蛋白相互作用。纯化和复性的重组蛋白的Western印迹特异性结合125I标记的层粘连蛋白，从egmo3推断的氨基酸序列衍生的合成肽也能结合，该合成肽在同源性上与67-LR的活性配体结合位点肽G相似。我们还从密切相关的物种多房棘球绦虫中分离出编码同源蛋白的cDNA的3'端。egmo3编码的多肽也与参与蛋白质合成的酸性核糖体蛋白类有大量同源性。因此，egmo3蛋白在细粒棘球绦虫中可能具有多种功能，既是层粘连蛋白结合分子，又在细胞分裂和生长中发挥作用。
