College of Life Sciences, Shenzhen Key Laboratory of Microbial Genetic Engineering, Shenzhen University, Shenzhen 518060, China.
Int J Mol Sci. 2013 Nov 11;14(11):22233-45. doi: 10.3390/ijms141122233.
Selenium, an essential trace element for human health, mainly exerts its biological function through selenoproteins. Selenoprotein M (SelM) is one of the highly expressed selenoproteins in the brain, but its biological effect and molecular mechanism remain unclear. Thus, the interactive protein of SelM was investigated in this paper to guide further study. In order to avoid protein translational stop, the selenocysteine-encoding UGA inside the open reading frame of SelM was site-directly changed to the cysteine-encoding UGC to generate the SelM' mutant. Meanwhile, its N terminal transmembrane signal peptide was also cut off. This truncated SelM' was used to screen a human fetal brain cDNA library by the yeast two-hybrid system. A new interactive protein of SelM' was found to be galectin-1 (Gal-1). This protein-protein interaction was further verified by the results of fluorescence resonance energy transfer techniques, glutathione S-transferase pull-down and co-immunoprecipitation assays. As Gal-1 plays important roles in preventing neurodegeneration and promoting neuroprotection in the brain, the interaction between SelM' and Gal-1 displays a new direction for studying the biological function of SelM in the human brain.
硒是人体健康所必需的微量元素，主要通过硒蛋白发挥其生物学功能。硒蛋白 M（SelM）是大脑中高度表达的硒蛋白之一，但它的生物学效应和分子机制尚不清楚。因此，本文研究了 SelM 的互作蛋白，以指导进一步的研究。为避免蛋白质翻译终止，SelM 开放阅读框内的硒代半胱氨酸编码 UGA 被定点突变为编码半胱氨酸的 UGC，从而产生 SelM'突变体。同时，其 N 端跨膜信号肽也被截断。该截断的 SelM'被用于酵母双杂交系统筛选人胎脑 cDNA 文库，发现 SelM'的一个新的互作蛋白为半乳糖凝集素-1（Gal-1）。荧光共振能量转移技术、谷胱甘肽 S-转移酶下拉和共免疫沉淀实验的结果进一步验证了这种蛋白-蛋白相互作用。由于 Gal-1 在预防脑内神经退行性变和促进神经保护方面发挥着重要作用，SelM'与 Gal-1 的相互作用为研究 SelM 在人脑内的生物学功能提供了新的方向。
