Sequence of picornavirus RNAs containing a radioiodinated 5'-linked peptide reveals a conserved 5' sequence

Virion RNA (vRNA) from poliovirus type 1 (PV1), poliovirus type 2 (PV2), and coxsackie virus B1 (Cox B1) were treated with proteinase K to remove all but a small peptide of the covalently attached 5' genome-linked virion protein (VPg). The peptide on these RNA molecules was then treated with Bolton-Hunter 125I reagent, which iodinates primary amine groups, in order to obtain specific 5'-terminal radioactive labeling. Sequences of 125I-labeled vRNAs were determined by using a set of base-specific RNases and a partial alkaline hydrolysis "ladder." The first 20 positions of these RNAs show a remarkable conservation of sequence. The initial 10 nucleotides are identical in PV1, PV2, and Cox B1, with the sequence VPg-pU-U-A-A-A-A-C-A-G-C. The next 10 nucleotides show a one-base difference between PV1 and PV2 and 50% homology between PV1 and Cox B1. This conserved 5' region may provide a recognition site for interaction between the viral mRNA and the host translation system.