High level expression of transgenes by use of 5′-untranslated region of the Arabidopsis thaliana arabinogalactan-protein 21 gene in dicotyledons

Abstract

For higher expression of a foreign gene in plant cells, it is important to optimize nucleotide sequences corresponding to 5′-untranslated region (5′-UTR), because it usually has great impacts on the expression of the gene mainly at the translational level. In this study, with an aim to find useful 5′-UTRs, thirty nine 5′-UTRs derived from Arabidopsis thaliana genes were tested by transient expression of firefly luciferase (Fluc), and that of A. thaliana arabinogalactan-protein 21 (AtAGP21) gene was selected for further analyses. Its activity was either equaling or surpassing that of known translational enhancer, A. thaliana alchol dehydrogenase (AtADH) 5′-UTR in dicotyledons, and was further improved by the optimizing sequence context of the initiating codon (－3 to －1 of AUG). Finally, we also found that the modified AtAGP21 5′-UTR was useful in recombinant expression of horseradish peroxidase (HRP) in tobacco cultured cells, and the yield was as much as 23 mg l^－1 culture medium in seven days.