Genome binding/occupancy profiling by high throughput sequencing
Summary
In response to DNA replication stress, DNA replication checkpoint is activated to maintain fork stability, a process critical for maintenance of genome stability. However, how DNA replication checkpoint regulates replication forks remain elusive. Here we show that Rad53, a highly conserved replication checkpoint kinase, functions to couple leading and lagging strand DNA synthesis. In wild type cells under HU induced replication stress, synthesis of lagging strand, which contains ssDNA gaps, is comparable to leading strand DNA. In contrast, synthesis of lagging strand is much more than leading strand, and consequently, leading template ssDNA coated with ssDNA binding protein RPA was detected in rad53-1 mutant cells, suggesting that synthesis of leading strand and lagging strand DNA is uncoupled. Mechanistically, we show that replicative helicase MCM and leading strand DNA polymerase Pole move beyond actual DNA synthesis and that an increase in dNTP pools largely suppresses the uncoupled leading and lagging strand DNA synthesis. Our studies reveal an unexpected mechanism whereby Rad53 regulates replication fork stability.
Overall design
We synchronized yeast cells (Wile type and other mutant cells) at G1 and released into early S phase in the presence of BrdU, and hydroxyurea (HU). We then performed BrdU immunoprecipitation using anti-BrdU antibodies following single-strand DNA library preparation and sequencing. We also performed protein ChIP followed by single-strand DNA sequencing (ChIP-ssSeq) for MCM6 and Pol ɛ. The sequencing tag was mapped to both Watson (red) and Crick (blue) strands of the reference genome.
Less...
More...