Costa F C, Oliva M A V, de Jesus T C L, Schenkman S, Thiemann O H
Laboratory of Protein Crystallography and Structural Biology, Physics Institute of São Carlos, University of São Paulo, Brazil.
Mol Biochem Parasitol. 2011 Nov;180(1):47-50. doi: 10.1016/j.molbiopara.2011.04.007. Epub 2011 Jun 23.
Selenoproteins are characterized by the incorporation of at least one amino acid selenocysteine (Sec-U) encoded by in-frame UGA stop codons. These proteins, as well as the components of the Sec synthesis pathway, are present in members of the bacteria, archaea and eukaryote domains. Although not a ubiquitous pathway in all organisms, it was also identified in several protozoa, including the Kinetoplastida. Genetic evidence has indicated that the pathway is non-essential to the survival of Trypanosoma growing in non-stressed conditions. By analyzing the effects of RNA interference of the Trypanosoma brucei selenophosphate synthetase SPS2, we found a requirement under sub-optimal growth conditions. The present work shows that SPS2 is involved in oxidative stress protection of the parasite and its absence severely hampers the parasite survival in the presence of an oxidizing environment that results in an apoptotic-like phenotype and cell death.
硒蛋白的特征是至少包含一个由框内UGA终止密码子编码的氨基酸硒代半胱氨酸（Sec-U）。这些蛋白质以及Sec合成途径的组分存在于细菌、古菌和真核生物域的成员中。尽管在所有生物体中并非普遍存在的途径，但它也在几种原生动物中被鉴定出来，包括动质体目。遗传证据表明，该途径对于在非应激条件下生长的锥虫的存活并非必不可少。通过分析布氏锥虫硒代磷酸合成酶SPS2的RNA干扰效应，我们发现在次优生长条件下存在需求。目前的研究表明，SPS2参与寄生虫的氧化应激保护，其缺失严重阻碍寄生虫在氧化环境中存活，导致类似凋亡的表型和细胞死亡。
