The longer version of Arabidopsis thaliana heat shock protein 18.2 gene terminator contributes to higher expression of stably integrated transgenes in cultured tobacco cells

In order to achieve higher expression of a transgene, it is important to optimize not only the promoter, 5'-untranslated region (UTR), and localization signal, but also the transcriptional terminator. We previously reported that the terminator derived from the Arabidopsis thaliana heat shock protein 18.2 gene (HSPT) increases gene expression in various plant species. In this study, with the goal of further increasing the expression level of transgenes, we evaluated a longer version of HSPT, corresponding to the 878 bp downstream of the stop codon, in cultured tobacco cells. The longer version of HSPT increased the expression levels of various genes including Renilla reniformis luciferase, Photinus pyralis luciferase, horseradish (Armoracia rusticana) peroxidase, and the non-toxic B subunit of Stx2e, a candidate vaccine protein for pig edema disease. This effect was not observed in a transient expression system. This element represents a useful tool for expression of transgenes integrated into the nuclear genome in plant cells.