The Highly Conserved Codon following the Slippery Sequence Supports -1 Frameshift Efficiency at the HIV-1 Frameshift Site

Mathew, Suneeth F.; Crowe-McAuliffe, Caillan; Graves, Ryan; Cardno, Tony S.; McKinney, Cushla; Poole, Elizabeth S.; Tate, Warren P.

Cellular levels of eRF1 mRNA were increased 250-fold, resulting in a 4-fold increase in eRF1 protein 48 h after transfection (Fig. 5A and B) . At a strong termination signal (UGAAAG) with very low readthrough (0.085%), the over-expressed eRF1 caused an apparent small decrease in readthrough that was not statistically significant (P > 0.05) (Fig. 5C) . At a weak stop signal (UGACUG) readthrough reduction was more robust, from 1.4% to 1.0% (P < 0.05). Co-transfection of the eRF1 vector, pcDNA-eRF1, with the antizyme +1 frameshift element resulted in a 30% lower +1 frameshift efficiency compared with control transfections (Fig. 5D ). This demonstrated that over-expressing eRF1 can change the balance towards termination and against frameshifting at the UGA codon.