Weiland Malin E-L, McArthur Andrew G, Morrison Hilary G, Sogin Mitchell L, Svärd Staffan G
Microbiology and Tumor Biology Center, Karolinska Institutet, Stockholm, Sweden.
Int J Parasitol. 2005 May;35(6):617-26. doi: 10.1016/j.ijpara.2004.12.009. Epub 2005 Feb 9.
Through a genome survey and phylogenetic analysis, we have identified and sequenced 14 new coding regions for alpha-giardins in Giardia lamblia. These proteins are related to annexins and comprise a multi-gene family with 21 members. Many alpha giardins are highly expressed proteins that are very immunogenic during acute giardiasis in humans. However, little is known about the function of these proteins. By using PCR with different combinations of gene-specific primers, we demonstrated that several of the genes localised to the same chromosomal fragment. These data point towards a molecular evolution through gene duplication and subsequent functional divergence. Semi-quantitative reverse transcriptase-PCR analysis of the Giardia life cycle revealed large differences in mRNA expression levels of the alpha giardins. Epitope tagging of the alpha-giardins localised them to different cytoskeletal components, such as the flagella and the adhesive disc, but also to the plasma membrane. These localisation experiments suggest alpha-giardins play a role in cell motility, attachment and membrane stability.
通过基因组调查和系统发育分析，我们在蓝氏贾第鞭毛虫中鉴定并测序了14个新的α-贾第蛋白编码区。这些蛋白质与膜联蛋白相关，构成了一个有21个成员的多基因家族。许多α-贾第蛋白是高表达蛋白，在人类急性贾第虫病期间具有很强的免疫原性。然而，这些蛋白质的功能鲜为人知。通过使用基因特异性引物的不同组合进行PCR，我们证明了其中几个基因定位于同一染色体片段。这些数据表明通过基因复制和随后的功能分化实现了分子进化。对贾第虫生命周期的半定量逆转录PCR分析显示，α-贾第蛋白的mRNA表达水平存在很大差异。α-贾第蛋白的表位标签将它们定位于不同的细胞骨架成分，如鞭毛和粘附盘，也定位于质膜。这些定位实验表明α-贾第蛋白在细胞运动、附着和膜稳定性中发挥作用。
