CLONING, IDENTIFICATION AND EXPRESSION OF FERRITIN HEAVY CHAIN FROM CHINESE GIANT SALAMANDERS, ANDRIAS DAVIDIANUS

Ferritin is an important iron storage protein in organism with the function of detoxification, anti-inflammatory and anti-stress. In this study, the full length cDNA of Andrias davidianus ferritin heavy chain (AdFTH) was isolated from the constructed skin cDNA library, and it consists of 864 bp including an open reading frame (ORF) of 531 bp, a 5'-terminal untranslated region (UTR) of 120 bp, and a 3'-UTR of 214 bp. The predicted molecular weight is 20.6 kD and the theoretical isoelectric point is 5.41 with no amino-terminal signal peptide and transmembrance domain. A complete iron-responsive element (IRE) locates at the 5'-UTR corresponding to the nucleotide sequence at the positions of the 2251 bp. The homology and phylogenetic analysis of FTH among other animals indicated that it is an evolutionarily conserved gene. The results of quantitative real time PCR demonstrated that AdFTH was ubiquitously expressed, and the highest level of adFTH was observed in the liver from total 9 tissues, which may support that the liver is the major organ for the storage and metabolism of iron in Andrias davidianus. Additionally, a recombinant expression vector pET32a-AdFTH was constructed, and the recombinant protein was purified using the expression system in E. coli BL21 (DE3) pLysS and Ni2+-chelating chromatography. The purified recombinant AdFTH protein (rAdFTH) promoted iron oxidation and iron uptake in vitro, suggesting that the rAdFTH protein may be used to produce the monoclonal antibodies and provide a foundation for further investigation of the physiological function of AdFTH.