UC Santa Cruz

Although the ribosome is known to function as a helicase, unwinding downstream secondary structured messenger RNA while simultaneously translating upstream mRNA into a polypeptide chain, the intricacies of these unwinding interactions are not well understood. mRNA containing secondary structure can result in ribosomal pausing, as well as frameshifting and mRNA decay pathways. While previous structural studies imply delays due to issues with mRNA-tRNA translocation, the precise interactions, and resulting events when an mRNA stem-loop is poised at the entry tunnel of the ribosome, remain elusive. We have designed an mRNA specifically configured to highlight these interactions. Our results illustrate where we propose the ribosome should be stalled to elicit unwinding activity and set the stage for the determination of a new cryo-EM structure which should illuminate mechanistic details of the ribosomal helicase.