Molecular cloning, characterization and mRNA expression analysis of a novel selenoprotein: avian selenoprotein W from chicken.

In this study, a novel avian selenoprotein W (SelW) gene was cloned from chicken cerebral tissue. The complete nucleotide sequence of the gene contained a 258 bp open reading frame encoding 85 amino acids. Bioinformatics approaches identified the chicken SelW protein is characterized by a β-α-β-β-β-α secondary structure pattern, wherein β1 and β2 are parallel strands forming a classical β1-α1-β2 motif, which is also observed in thioredoxin-like fold proteins. The protein has a candidate CXXU redox motif which is located in the loop (residues 10-13) between β1 and α1. The 3D structural similarity between mouse and chicken SelW protein suggests that the proteins may exhibit similar functions. Additionally, a selenocysteine insertion sequence (SECIS) element was found in the 3'-untranslated region of the SelW mRNA. The SECIS element was classified as form II. Moreover, we analyzed the mRNA expression of SelW genes in 36 different tissues of 60-day-old chickens; the expression of SelW was detected in all tissues, indicating that SelW is expressed widely in chicken tissue. Hence, we suggest that SelW might play an important role in the biochemical functions of Se in birds.