Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC- CONICET, Friuli 2434, Córdoba, Argentina.
Biomolecules. 2012 Jul 25;2(3):312-30. doi: 10.3390/biom2030312.
Post-translational modifications are able to regulate protein function and cellular processes in a rapid and reversible way. SUMOylation, the post-translational modification of proteins by the addition of SUMO, is a highly conserved process that seems to be present in modern cells. However, the mechanism of protein SUMOylation in earlier divergent eukaryotes, such as Giardia lamblia, is only starting to become apparent. In this work, we report the presence of a single SUMO gene encoding to SUMO protein in Giardia. Monoclonal antibodies against recombinant Giardia SUMO protein revealed the cytoplasmic localization of native SUMO in wild-type trophozoites. Moreover, the over-expression of SUMO protein showed a mainly cytoplasmic localization, though also neighboring the plasma membrane, flagella, and around and even inside the nuclei. Western blot assays revealed a number of SUMOylated proteins in a range between 20 and 120 kDa. The genes corresponding to putative enzymes involved in the SUMOylation pathway were also explored. Our results as a whole suggest that SUMOylation is a process conserved in the eukaryotic lineage, and that its study is significant for understanding the biology of this interesting parasite and the role of post-translational modification in its evolution.
蛋白质翻译后修饰能够快速、可逆地调节蛋白质功能和细胞过程。SUMO 化是蛋白质翻译后通过添加 SUMO 进行的修饰，这是一个高度保守的过程，似乎存在于现代细胞中。然而，在更早的分化真核生物（如蓝氏贾第鞭毛虫）中，蛋白质 SUMO 化的机制才刚刚开始显现。在这项工作中，我们报告了在贾第虫中存在一个编码 SUMO 蛋白的单一 SUMO 基因。针对重组贾第虫 SUMO 蛋白的单克隆抗体揭示了野生型滋养体中天然 SUMO 的细胞质定位。此外，SUMO 蛋白的过表达显示主要是细胞质定位，尽管也靠近质膜、鞭毛，以及围绕和甚至在核内。Western blot 分析显示，在 20 到 120 kDa 之间有许多 SUMO 化蛋白。还探索了与 SUMO 化途径中假定酶相关的基因。我们的研究结果表明，SUMO 化是真核生物谱系中保守的过程，其研究对于理解这种有趣寄生虫的生物学以及翻译后修饰在其进化中的作用具有重要意义。
