Oral Presentation The 35th Biennial Conference of the Society of Crystallographers in Australia and New Zealand 2024 (Crystal 35)

Structural basis of transcriptional regulation by a nascent RNA element, HK022 putRNA (109000)

Seungha Hwang 1 , Paul Dominic B. Olinares 2 , Jimin Lee 1 , Jinwoo Kim 1 , Brian T. Chait 2 , Rodney A. King 3 , Jin Young Kang 1
  1. KAIST, Daejon, DAEJON, South Korea
  2. The Rockfeller University, New York, NY, United States
  3. Giology, Western Kentucky University, Bowling Green, KY, United States

Transcription, in which RNA polymerases (RNAPs) produce RNA from DNA, is the first step of gene expression. As such, it is highly regulated either by trans- elements like protein factors and/or by cis-elements like specific sequences on the DNA. Lambdoid phage HK022 contains a cis-element, put, which sup- presses pausing and termination during transcription of the early phage genes. The putRNA transcript solely performs the anti-pausing/termination activities by interacting directly with the E.coli RNAP elongation complex (EC) by an unknown structural mechanism. In this study, we reconstituted putRNA- associated ECs and determined the structures using cryo-electron microscopy. The determined structures of putRNA-associated EC, putRNA-absent EC, and σ70-bound EC suggest that the putRNA interaction with the EC counteracts swiveling, a conformational change previously identified to promote pausing and σ70 might modulate putRNA folding via σ70-dependent pausing during elongation.