Analysis of the mechanism of activation and co-translational insertion of an essential trace element, selenium, into polypeptide

点击翻译按钮获取中文摘要

Selenium, an essential trace element, is incorporated into a specific position of selenoprotein in the form of selenocysteine residues and plays a various important roles in organisms. In this study, we investigated the function of proteins involved in the metabolism of selenium.1.Selenocysteine lyase (SCL) catalyzes the decomposition of L-selenocysteine into L-alanine and selenium. We employed the yeast two-hybrid system using mouse SCL as a bait to search for a protein(s) that interacts with SCL. We identified major urinary protein (MUP) as a potential partner of SCL. Our analysis revealed that SCL inhibits the interaction between MUP and 2-naphtol in vitro.2.The mouse SCL gene was expressed in the cytosol or chloroplast of Arabidopsis thaliana. The selenium-tolerance of the plant was greatly improved, indicating that SCL is useful for phyroremediation.3.The distribution of selenium and selenoprotein mRNAs in moue brain were determined by quantification of selenium and quantitative RT-PCR, respectively.4.siRNAs targeted to SCL were transfected with human HeLa cells and mouse Al cells to knock-down the expression of SCL. We found that siRNAs against SCL decreases the expression of selenoproteins in both cells. The results suggest that SCL is involved in the biosynthesis of selenoprotein.5.Rat SCL was crystallized and its three-dimensional structure was solved. The structure revealed that SCL has a catalytically essential cysteine residue on a extended lobe.