Cabral Fernanda J, Pereira Olavo S, Silva Camila S, Guerra-Sá Renata, Rodrigues Vanderlei
Department of Biochemistry and Immunology, School of Medicine, University of São Paulo, Av Bandeirantes, 3900, Monte Alegre, Ribeirão Preto, São Paulo, Brazil.
Parasitol Int. 2008 Jun;57(2):172-8. doi: 10.1016/j.parint.2007.12.003. Epub 2007 Dec 15.
The sumoylation pathway is a post-translational modification of nuclear proteins widespread among several organisms. SMT3C is the main protein involved in this process and it is covalently conjugated to a diverse assortment of nuclear protein targets. To date, 3 SUMO paralogues (SMT3C, A/B) have been characterized in mammals and plants. In this work we characterized two SUMO related genes, named SMT3B and SMT3C throughout Schistosoma mansoni life cycle. The SmSMTB/C encodes for proteins sharing significant amino acid homology with SMT3. Phylogenetical analyses revealed that both SmSMT3B/C are distinct proteins. Additionally, SmSMT3B and C are expressed in cercariae, adult worms, eggs and schistosomula however SmSMT3C gene showed an expression level 7 to 9 fold higher than SmSMT3B in eggs, schistosomula and adult worms. The comparison between the SmSMT3C genomic and cDNA sequences established that the encoding sequence is interrupted by 3 introns of 70, 37 and 36 bp. Western Blot has shown SMT3 conjugates are present in nuclear and total protein fractions of adults and cercariae. Therefore our results suggest a functional sumoylation pathway, and the presence of two paralogues also suggests the specificity of substrates for SMT3 in S. mansoni.
SUMO化途径是一种在多种生物体中广泛存在的核蛋白翻译后修饰。SMT3C是参与该过程的主要蛋白质，它与多种核蛋白靶标共价结合。迄今为止，在哺乳动物和植物中已鉴定出3种SUMO旁系同源物（SMT3C、A/B）。在这项工作中，我们在曼氏血吸虫的整个生命周期中鉴定了两个与SUMO相关的基因，分别命名为SMT3B和SMT3C。SmSMTB/C编码的蛋白质与SMT3具有显著的氨基酸同源性。系统发育分析表明，SmSMT3B/C都是不同的蛋白质。此外，SmSMT3B和C在尾蚴、成虫、虫卵和童虫中均有表达，然而在虫卵、童虫和成虫中，SmSMT3C基因的表达水平比SmSMT3B高7至9倍。SmSMT3C基因组序列和cDNA序列的比较表明，编码序列被3个分别为70、37和36 bp的内含子打断。蛋白质免疫印迹显示，SMT3缀合物存在于成虫和尾蚴的核蛋白和总蛋白组分中。因此，我们的结果提示存在功能性的SUMO化途径，并且两个旁系同源物的存在也提示了曼氏血吸虫中SMT3底物的特异性。
