Helicase promotes replication re-initiation from an RNA transcript

Nat Commun. 2018 Jun 13;9(1):2306. doi: 10.1038/s41467-018-04702-x.


To ensure accurate DNA replication, a replisome must effectively overcome numerous obstacles on its DNA substrate. After encountering an obstacle, a progressing replisome often aborts DNA synthesis but continues to unwind. However, little is known about how DNA synthesis is resumed downstream of an obstacle. Here, we examine the consequences of a non-replicating replisome collision with a co-directional RNA polymerase (RNAP). Using single-molecule and ensemble methods, we find that T7 helicase interacts strongly with a non-replicating T7 DNA polymerase (DNAP) at a replication fork. As the helicase advances, the associated DNAP also moves forward. The presence of the DNAP increases both helicase's processivity and unwinding rate. We show that such a DNAP, together with its helicase, is indeed able to actively disrupt a stalled transcription elongation complex, and then initiates replication using the RNA transcript as a primer. These observations exhibit T7 helicase's novel role in replication re-initiation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacteriophage T7 / enzymology
  • Bacteriophage T7 / genetics
  • DNA Helicases / metabolism*
  • DNA Replication / physiology*
  • DNA, Viral / genetics
  • DNA, Viral / metabolism
  • DNA-Directed DNA Polymerase / metabolism
  • DNA-Directed RNA Polymerases / metabolism
  • Escherichia coli / genetics
  • Escherichia coli / metabolism
  • Models, Biological
  • RNA, Viral / genetics
  • RNA, Viral / metabolism
  • Transcription, Genetic


  • DNA, Viral
  • RNA, Viral
  • DNA-Directed RNA Polymerases
  • DNA-Directed DNA Polymerase
  • DNA Helicases