Molecular characteristics and expression analysis of ferritin gene from Sinonovacula constricta

Abstract:

One EST sequence with high homology with ferritin gene of other species was found from the cDNA library of Sinonovacula constricta and then the complete expression sequence was obtained by PCR. The cDNA of this gene was 1 106 bp, which consists of a 128 bp 5′untranslated region (UTR), a 669 bp open reading frame (ORF) and a 309 bp 3′ UTR. The translated protein is composed of 222 amino acids，containing a signal peptide of 17 amino acids, with 25.47 ku molecular weight，and its calculated isoelectric point was 5.48. Sequence analysis of the protein revealed that the protein contained a highly conserved motif for the ferroxidase center, which consisted of seven residues of a typical vertebrate heavy chain ferritin, but lacking a N glycosylattion site and an iron responsive element (IRE) with a typical stem loop structure in the 5′UTR position. This gene is H subunit ferritin gene and designated as ScFERs.Phylogenetic analysis suggested that the same species of different subsets of ferritin first gathered together, and then clustered with other marine animals. ScFERs of S.constricta clustered with LjFERs of L. japonica firstly, and then clustered with ScFER of S. constricta and MmFERs of M. meretrix. The quantitative reverse transcriptase (qRT PCR) analyses showed that the expression level of ScFERs gene was highest in liver, significantly higher than other tissues.The expression of ScFERs gene in liver tissue was up regulated following the challenge with Vibrio anguillarum and Vibrio parahaemolyticu, respectively. This study will be helpful for further understanding the structure and function of ferritin from S.constricta.