Cleavage of polypyrimidine tract-binding proteins by polioviral 3C(pro) generates fragments that redistribute to the cytoplasm and inhibit polioviral IRES-dependent translation.
Proteolytic cleavage of PTBs by polioviral 3Cpro inhibits IRES-dependent translation, potentially contributing to the molecular switch from translation to replication of polioviral RNA.
The translation of polioviral mRNA occurs through an internal ribosomal entry site (IRES). Several RNA-binding proteins, such as polypyrimidine tract-binding protein (PTB) and poly(rC)-binding protein (PCBP), are required for the poliovirus IRES-dependent translation. Here we report that a poliovirus protein, 3C(pro) (and/or 3CD(pro)), cleaves PTB isoforms (PTB1, PTB2, and PTB4). Three 3C(pro) target sites (one major target site and two minor target sites) exist in PTBs. PTB fragments generated by poliovirus infection are redistributed to the cytoplasm from the nucleus, where most of the intact PTBs are localized. Moreover, these PTB fragments inhibit polioviral IRES-dependent translation in a cell-based assay system. We speculate that the proteolytic cleavage of PTBs may contribute to the molecular switching from translation to replication of polioviral RNA.
Back et al. (Fri,) conducted a other in Poliovirus infection. Polioviral 3C(pro) cleavage of PTBs was evaluated on Polioviral IRES-dependent translation. Cleavage of polypyrimidine tract-binding proteins by polioviral 3C(pro) generates fragments that redistribute to the cytoplasm and inhibit polioviral IRES-dependent translation.