Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden.
Exp Parasitol. 2011 Apr;127(4):804-10. doi: 10.1016/j.exppara.2011.01.006. Epub 2011 Jan 26.
The molecular pathogenesis of the intestinal parasite Giardia intestinalis is still not fully understood but excretory-secretory products have been suggested to be important during host-parasite interactions. Here we used SDS-PAGE gels and MALDI-TOF analysis to identify proteins released by Giardia trophozoites during in vitro growth. Serum proteins (mainly bovine serum albumin) in the growth medium, bind to the parasite surface and they are continuously released, which interfere with parasite secretome characterization. However, we identified two released Giardia proteins: elongation factor-1 alpha (EF-1α) and a 58 kDa protein, identified as arginine deiminase (ADI). This is the first description of EF-1α as a released/secreted Giardia protein, whereas ADI has been identified in an earlier secretome study. Two genes encoding EF-1α were detected in the Giardia WB genome 35 kbp apart with almost identical coding sequences but with different promoter and 3' regions. Promoter luciferase-fusions showed that both genes are transcribed in trophozoites. The EF-1α protein localizes to the nuclear region in trophozoites but it relocalizes to the cytoplasm during host-cell interaction. Recombinant EF-1α is recognized by serum from giardiasis patients. Our results suggest that released EF-1α protein can be important during Giardia infections.
肠贾第虫的分子发病机制尚不完全清楚，但分泌/排泄产物在宿主-寄生虫相互作用中被认为是重要的。在这里，我们使用 SDS-PAGE 凝胶和 MALDI-TOF 分析来鉴定在体外生长过程中由滋养体释放的贾第虫蛋白。生长培养基中的血清蛋白（主要是牛血清白蛋白）结合到寄生虫表面，并不断释放，这干扰了寄生虫分泌组的特征描述。然而，我们鉴定了两种释放的贾第虫蛋白：延伸因子-1α（EF-1α）和一种 58 kDa 的蛋白，鉴定为精氨酸脱氨酶（ADI）。这是首次描述 EF-1α 作为一种释放/分泌的贾第虫蛋白，而 ADI 已在早期的分泌组研究中被鉴定。在贾第虫 WB 基因组中检测到两个编码 EF-1α的基因，它们相距 35 kbp，具有几乎相同的编码序列，但启动子和 3'区域不同。启动子荧光素酶融合显示这两个基因在滋养体中都被转录。EF-1α蛋白在滋养体中定位于核区，但在与宿主细胞相互作用时重新定位到细胞质。重组 EF-1α被贾第虫病患者的血清识别。我们的结果表明，释放的 EF-1α 蛋白在贾第虫感染过程中可能很重要。
