Exploring the Significance of the Human T‐cell Lymphotropic Virus Type‐1 pro‐pol Frameshift Site Pseudoknot

Programmed ribosomal frameshifting (PRF) is a common viral mechanism used to regulate the levels of viral enzymatic and structural proteins. PRF events are stimulated by cis ‐acting RNA elements within the viral transcript, occur during translation, and change the ribosomal reading frame. Each PRF occurs at a frameshift site that includes a “slippery” sequence, a spacer, and a downstream structure. The human T‐cell Lymphotropic Virus Type‐1 (HTLV‐1) retrovirus uses two, independent ‐1 PRF sites to express three of its viral enzymes. While the structure was previously predicted to be a pseudoknot, the importance of this structure to frameshifting has not been established. In this work, we are examining the importance of the frameshift site structure to HTLV‐1 pro‐pol frameshift stimulation. Specifically, we examined how mutations that change the RNA structure impact ‐1 PRF efficiency. We hypothesized that mutations that disrupted the pseudoknot structure would decrease the frameshift efficiency. Likewise, mutations that restored the pseudoknot structure should have no impact on frameshift efficiency. To test these hypotheses, we measured the frameshift efficiencies for several variant frameshift sites using an in vitro dual‐luciferase frameshift assay. Preliminary data suggests that when the pseudoknot structure is disrupted, there is a significant decrease in frameshift efficiency. Surprisingly, a mutation that restored pseudoknot formation increased the frameshift efficiency. These results are significant because they suggest that the pseudoknot structure plays a critical role in frameshift stimulation. Support or Funding Information NIH NIGMS SCORE SC2 Award (1SC2GM121197‐01) and Research Corporation for Science Advancement Cottrell Scholar Award (23983) This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .