Funding Organization(s): European Research Council (ERC), French Infrastructure for Integrated Structural Biology (FRISBI), Agence Nationale de la Recherche (ANR)
RNA can regulate its own synthesis without auxiliary proteins. For example, U-rich RNA sequences signal RNA polymerase (RNAP) to pause transcription and are required for transcript release at intrinsic terminators in all kingdoms of life. In contrast, the regulatory RNA putL suppresses pausing and termination in cis. However, how nascent RNA modulates its own synthesis remains largely unknown. We present cryo-EM reconstructions of RNAP captured during transcription of putL variants or an unrelated sequence at a U-rich pause site. Our results suggest how putL suppresses pausing and promotes its synthesis. We demonstrate that transcribing a U-rich sequence, a ubiquitous trigger of intrinsic termination, promotes widening of the RNAP nucleic-acid-binding channel. Widening destabilizes RNAP interactions with DNA and RNA to facilitate transcript dissociation reminiscent of intrinsic transcription termination. Surprisingly, RNAP remains bound to DNA after transcript release. Our results provide the structural framework to understand RNA-mediated intrinsic transcription termination.
Organizational Affiliation:
Department of Integrated Structural Biology, IGBMC, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), 67400 Illkirch, France; Université de Strasbourg, IGBMC UMR 7104-UMR-S 1258, 67400 Illkirch, France; CNRS, UMR 7104, 67400 Illkirch, France; Inserm, UMR-S 1258, 67400 Illkirch, France.
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