Poliovirus-encoded protease 2A(Pro) cleaves the TATA-binding protein does not inhibit host cell RNA polymerase II transcription in vitro

Transient expression of the poliovirus-encoded protease 2A(Pro) in eukaryotic cells results in inhibition of both cellular transcription and translation. The inhibition of transcription observed in cells expressing 2A(Pro) could be due to a primary effect dr secondary effect caused by inhibition of: translation. Because transcriptional activity of the TATA-binding protein (TBP) is drastically reduced in poliovirus-infected cells, we determined if 2A(Pro) is able to Cleave TBP in vitro. We demonstrate here that 2A(Pro) directly cleaves the single tyrosine-glycine bond at position 34 of TBP, This cleavage is also seen in poliovirus-infected HeLa cells. Surprisingly, despite TBP cleavage 2A(Pro) was unable to inhibit RNA polymerase II transcription in vitro. Under similar conditions, however, 2A(Pro) inhibited translation of a capped cellular mRNA in vitro. Thus, cleavage of TBP ai position 34 does not alter its transcriptional activity in vitro. These results suggest that inhibition of host cell RNA polymerase II transcription seen in cells transiently transfected with 2A(Pro) is due to host cell translational shutoff.