HOST-CELL PROTEINS BINDING TO DOMAIN-IV OF THE 5' NONCODING REGION OFPOLIOVIRUS RNA

Translation of poliovirus RNA occurs by the binding of ribosomes to an internal segment of RNA sequence within the 5' untranslated region of the viral RNA. This region is predicted to consist of six domains (I to VI) that possess complex secondary and tertiary structures. Domain IV is a large region in which alterations in the sequence or structure markedly reduce translational efficiency. In this study, we employed RNA mobility shift assays to demonstrate that a protein(s) from uninfe cted HeLa cell extracts, as well as from neuroblastoma extracts, inter acts with the domain IV structure. A mutation in domain TV caused redu ced binding of HeLa cell proteins and reduced translation both in vitr o and in vivo, suggesting that the binding of at least one of these pr oteins plays a role in the mechanism of viral translation. UV cross-li nking indicated that a protein(s) with a size of similar to 40 kDa int eracted directly with the RNA. Using streptavidin beads to capture bio tinylated RNA bound to proteins, we were able to visualize a number of HeLa and neuroblastoma cell proteins that interact with domain IV. Th ese proteins have molecular masses of similar to 39, similar to 40, an d similar to 42 kDa.