Custom-Designed, Degradation-Resistant Messenger RNAs in Yeast

Structured RNA elements that protect RNA transcripts from 5′→3′ degradation are becoming useful research tools. Here we show that exonuclease-resistant RNA structures (xrRNAs) from Flaviviruses can be used to protect heterologous messenger RNAs (mRNAs) from 5′→3′ degradation in budding yeast. Installation of xrRNAs ahead of a downstream internal ribosome entry site (IRES) leads to the accumulation of partially-degraded mRNAs that are substrates for cap-independent translation of a LacZ reporter, yielding a 30-fold increase in measured β-galactosidase activity. Additionally, by monitoring the translation of dual-luciferase reporters we show that xrRNA sequences do not interfere with the progression of an elongating ribosome. Combined these data indicate that xrRNA elements can be used in creative ways to stabilize RNAs with potentially useful applications.