Oral Presentation The 46th Lorne Conference on Protein Structure and Function 2021

Interactions of Poly-C-binding protein 2 with the poliovirus type I IRES (#2)

Jackie Wilce 1 , Simone Beckham 2 , Mehdi Youssefi Matak 1 , Hans Elmlund 1 , Matthew Belousoff 3 , Hariprasad Venugopal 3 , Neelam Shah 1 , Naveen Vankadari 1 , Bert Semler 4 , Matthew Wilce 3
  1. Biomedicine Discovery Institute, Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC, Australia
  2. La Trobe University, Melbourne
  3. Monash University, Melbourne
  4. University of California, Irvine

The poliovirus type I IRES is able to recruit ribosomal machinery for efficient translation of the viral genome only in the presence of host factor PCBP2 that binds to stem loop IV of the IRES. Upon production of sufficient viral protein, including viral protease 3CD, PCBP2 is cleaved and translation ceases, allowing the next stage of replication to commence. We have investigated the interaction of PCBP2 with the apical region of stem loop IV of poliovirus RNA before and after its cleavage. SEC-SAXS, SHAPE and hydroxyl-radical cleavage have been used to establish the changes in solution conformation, RNA flexibility and base accessibility that occur upon PCBP2 binding in comparison with its cleaved form. PCBP2 stabilises the SLIV structure, but upon cleavage the remaining complex becomes more flexible and of lower affinity. Together this study sheds light on the structural features of the PCBP2/SLIV complex vital for ribosomal docking, and the way that this is regulated following translation of the poliovirus genome.