5′ Untranslated region of theHSP18.2 gene contributes to efficient translation in plant cells

Abstract

Maximizing the amount of protein translated per unit mRNA is an important goal in establishing expression systems. The 5′ untranslated region (5′-UTR) of mRNA is known to play an important role in determining the rate of translation. The full length 5′-UTR from theArabidopsis thaliana heat shock protein (HSP) gene,HSPI8.2 gene, was inserted into the cloning site between the cauliflower mosaic virus 35S RNA promoter and β-glucuronidase (GUS) gene in the pBI221 plasmid. When this construct was transfected intoNicotiana tabacum (tobacco) BY-2 protoplasts, the level of protein was about 10-fold higher than that of unmodified pB1221. The accumulation of each transcript was the same level. We also demonstrated that the 5′-UTR of theHSP18.2 gene enhances the rate of translation in stable transgenic BY-2 clones andArabidopsis T87 protoplasts. The 5′-UTRs of the otherArabidopsis HSP genes —HSP17.4, HSP81-1,HSP81-2, andHSP81-3 — also conferred efficient translation. These 5′-UTRs ofHSP genes may be of use in increasing the expression of foreign proteins. In combination with a strong promoter, it can be used in the development of efficient protein production systems.