Genetic Selection of Poliovirus 2Apro-Binding Peptides

The yeast two-hybrid system has been used to identify mammalian clones that interact with poliovirus 2A proteinase (2A^pro). Eight clones which encode previously unidentified human proteins were selected from a HeLa cell cDNA expression library. In addition, five clones encoding short peptides that interact with poliovirus 2A^pro were also identified. The lengths of these peptides range from 6 to 30 amino acids, but all of them contain the Leu-X-Thr-Z motif (X represents any amino acid; Z represents a hydrophobic residue). This sequence is invariably located just at the carboxy terminus of each peptide. This approach raises the possibility of designing substrate analogue inhibitors of 2A^pro. Thus, two nonhydrolyzable peptides containing the Leu-X-Thr-Z motif prevented cleavage of eukaryotic initiation factor 4G by poliovirus 2A^pro in vitro. A more general method for identifying peptides with antiproteinase activity is discussed.