Optical tweezers were used to track single molecules of two different classes of RNA polymerase as they transcribe DNA into RNA. She shows that RNAP I (which transcribes ribosomal RNA) and RNAP II (which transcribes messenger RNA) both exhibit backtracking dependent pauses and are able to recover from short backtracks via one-dimensional diffusion. Furthermore, they […]

The essential transcription initiation factor TFIIH translocates along double-stranded DNA. The Ssl2 subunit, previously thought to act as a helicase to convert dsDNA into ssDNA actually walks along dsDNA without unwinding. This explains structural results showing that Ssl2 does not contact the site of initial DNA unwinding during initiation and suggests an indirect mechanism of […]