Interaction of RNA polymerase II fork loop 2 with downstream non-template DNA regulates transcription elongation.

摘要: Fork loop 2 is a small semiconservative segment of the larger fork domain in second largest Rpb2 subunit RNA polymerase II (Pol II). This flexible loop, juxtaposed at leading edge transcription bubble, has been proposed to participate DNA strand separation, translocation along DNA, and NTP loading Pol during elongation. Here we show that mutant carrying deletion part not lethal yeast. The mutation exhibits no defects melting vitro but confers moderate decrease catalytic activity enzyme caused by impaired sequestration substrate active center prior catalysis. In structural model elongation complex, directly interacts with an unpaired residue non-template one nucleotide ahead from (the i+2 position). We showed elimination this putative interaction replacement abasic site inhibits same degree as 2. detectable effect on enzyme. provide direct evidence facilitates through adjacent involved II.