Cloning, expression and characterization of translationally controlled tumor protein (TCTP) gene from flatfish turbot (Scophthalmus maximus)

Abstract

A full-length cDNA encoding translationally controlled tumor protein of marine flatfish turbot (Scophthalmus maximus), SmTCTP, was isolated with rapid amplification of cDNA Ends (RACE). SmTCTP consisted of a 5′ untranslated region (UTR) of 84 bp, a 3′ UTR of 451 bp and an open reading frame (ORF) of 513 bp, encoding a protein of 170 amino acid residues, which contained two signature sequences of TCTP family. The 5′UTR of SmTCTP started with a 5′-terminal oligopyrimidine tract (5′-TOP), a typical feature for translationally controlled mRNAs. The deduced amino acid sequence of SmTCTP was similar to the other known vertebrate TCTPs in a range of 58.8% to 64.1%. The length of fish TCTPs was diverse among species, e.g., TCP of turbot and sea perch (Lateolabrax japonicus) is 170 aa in length, while that of zebrafish (Danio rerio) and rohu (Labeo rohita) is 171 aa in length. Northern blot analysis revealed that SmTCTP has only one type of mRNA. Its expression level in albino skin was slightly higher than that in normal skin. We constructed the pET30a-SmTCTP expression plasmid. The recombinant protein of His-tag SmTCTP was over-expressed in E. coli, purified and identified with peptide mass fingerprinting. These results may pave the way of further investigation of the biological function of TCTP in fish.