Mycobacterial HelD is a nucleic acids-clearing factor for RNA polymerase

Tomáš Kouba, Tomáš Koval’, Petra Sudzinová, Jiří Pospíšil, Barbora Brezovská, Jarmila Hnilicová, Hana Šanderová, Martina Janoušková, Michaela Šiková, Petr Halada, Michal Sýkora, Ivan Barvík, Jiří Nováček, Mária Trundová, Jarmila Dušková, Tereza Skálová, URee R. Chon, Katsuhiko S. Murakami, Jan Dohnálek, Libor Krásný

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


RNA synthesis is central to life, and RNA polymerase (RNAP) depends on accessory factors for recovery from stalled states and adaptation to environmental changes. Here, we investigated the mechanism by which a helicase-like factor HelD recycles RNAP. We report a cryo-EM structure of a complex between the Mycobacterium smegmatis RNAP and HelD. The crescent-shaped HelD simultaneously penetrates deep into two RNAP channels that are responsible for nucleic acids binding and substrate delivery to the active site, thereby locking RNAP in an inactive state. We show that HelD prevents non-specific interactions between RNAP and DNA and dissociates stalled transcription elongation complexes. The liberated RNAP can either stay dormant, sequestered by HelD, or upon HelD release, restart transcription. Our results provide insights into the architecture and regulation of the highly medically-relevant mycobacterial transcription machinery and define HelD as a clearing factor that releases RNAP from nonfunctional complexes with nucleic acids.

Original languageEnglish (US)
Article number6419
JournalNature communications
Issue number1
StatePublished - Dec 2020

All Science Journal Classification (ASJC) codes

  • General Chemistry
  • General Biochemistry, Genetics and Molecular Biology
  • General Physics and Astronomy


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