Programmed -1 ribosomal frameshifting (-1RF) is usually regulated by a slippery sequence and an RNA secondary structure but can be affected by the slippery sequence combined with translational perturbation. Dramatic increases of -1RF efficiencies arise from the slippery sequences in [PSI+], an epigenetic modifier of translation termination fidelity. Curing of [PSI+] abolished such increases of -1RF efficiency. Enhanced -1RF frequency at the slippery sequences could be another physiological effect induced directly or indirectly by the perturbation of the translation process in [PSI+] cells.