Characterization of a TaJ Gene from Wheat

A novel J-domain protein gene was cloned from wheat (Triticum aestivum L.) using RT-PCR technology and named as TaJ. The J-domain protein is defined by the presence of a J-domain. The cDNA of T. aestivum gene, TaJ (GenBank accession number: DQ789026), was 1263 bp and contained a complete open reading frame (ORF) encoding a J-domain protein of 420 amino acid residues. The predicted amino acid sequence of TaJ possesses three functionally essential domains: the Nterminal J-domain which includes the highly conserved HPD tripeptide, an adjacent domain that is rich in glycine and phenylalanine residues (G/F) and a Cysteine-rich zinc-finger domain with four repeats of CxxCxGxG that is important for protein interactions. The C-terminal of TaJ was -CAQQ, a farnesylation motif. The full-length deduced amino acid sequence of TaJ is highly homologous to J-domain proteins from various plant species. Southern blot analysis indicated that a single copy of TaJ existed in wheat genome. The expression pattern of TaJ performed by real-time PCR demonstrated that heat shock (HS) at 37°C induced the expression of TaJ rapidly and strongly, but the response of the TaJ gene to cold stress was much slower than that to HS. Tissue-specific expression analysis showed that the expression level of TaJ gene was much higher in leaves than that in roots.