Thermus thermophilus Argonaute Functions in the Completion of DNA Replication

Samson M. Jolly, Ildar Gainetdinov, Karina Jouravleva, Han Zhang, Lara Strittmatter, Shannon M. Bailey, Gregory M. Hendricks, Avantika Dhabaria, Beatrix Ueberheide, Phillip D. Zamore

Research output: Contribution to journalArticlepeer-review


In many eukaryotes, Argonaute proteins, guided by short RNA sequences, defend cells against transposons and viruses. In the eubacterium Thermus thermophilus, the DNA-guided Argonaute TtAgo defends against transformation by DNA plasmids. Here, we report that TtAgo also participates in DNA replication. In vivo, TtAgo binds 15- to 18-nt DNA guides derived from the chromosomal region where replication terminates and associates with proteins known to act in DNA replication. When gyrase, the sole T. thermophilus type II topoisomerase, is inhibited, TtAgo allows the bacterium to finish replicating its circular genome. In contrast, loss of gyrase and TtAgo activity slows growth and produces long sausage-like filaments in which the individual bacteria are linked by DNA. Finally, wild-type T. thermophilus outcompetes an otherwise isogenic strain lacking TtAgo. We propose that the primary role of TtAgo is to help T. thermophilus disentangle the catenated circular chromosomes generated by DNA replication.

Original languageEnglish (US)
Pages (from-to)1545-1559.e18
Issue number6
StatePublished - Sep 17 2020


  • Argonaute
  • DNA replication
  • RNA silencing
  • Thermus thermophilus
  • TtAgo
  • decatenation
  • gyrase
  • pAGO
  • terminus of replication
  • topoisomerase

ASJC Scopus subject areas

  • General Biochemistry, Genetics and Molecular Biology


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