We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Post-replicative nick translation occurs on the lagging strand during prolonged depletion of DNA ligase I in Saccharomyces cerevisiae.
- Authors
Koussa, Natasha C.; Smith, Duncan J.
- Abstract
During lagging-strand synthesis, strand-displacement synthesis by DNA polymerase delta (Pol ∂), coupled to nucleolytic cleavage of DNA flap structures, produces a nick-translation reaction that replaces the DNA at the 5' end of the preceding Okazaki fragment. Previous work following depletion of DNA ligase I in Saccharomyces cerevisae suggests that DNA-bound proteins, principally nucleosomes and the transcription factors Abf1/Rap1/Reb1, pose a barrier to Pol ∂ synthesis and thereby limit the extent of nick translation in vivo. However, the extended ligase depletion required for these experiments could lead to ongoing, non-physiological nick translation. Here, we investigate nick translation by analyzing Okazaki fragments purified after transient nuclear depletion of DNA ligase I in synchronized or asynchronous Saccharomyces cerevisiae cultures. We observe that, even with a short ligase depletion, Okazaki fragment termini are enriched around nucleosomes and Abf1/Reb1/Rap1-binding sites. However, protracted ligase depletion leads to a global change in the location of these termini, moving them toward nucleosome dyads from a more upstream location and further enriching termini at Abf1/Reb1/Rap1-binding sites. In addition, we observe an under-representation of DNA derived from DNA polymerase alpha--the polymerase that initiates Okazaki fragment synthesis--around the sites of Okazaki termini obtained from very brief ligase depletion. Our data suggest that, while nucleosomes and transcription factors do limit strand-displacement synthesis by Pol ∂ in vivo, post-replicative nick translation can occur at unligated Okazaki fragment termini such that previous analyses represent an overestimate of the extent of nick translation occurring during normal lagging-strand synthesis.
- Subjects
SACCHAROMYCES cerevisiae; DNA polymerases; DNA synthesis; DNA structure; NUCLEAR DNA
- Publication
G3: Genes | Genomes | Genetics, 2021, Vol 11, Issue 8, p1
- ISSN
2160-1836
- Publication type
Article
- DOI
10.1093/g3journal/jkab205