Dominic Bazzano, Stephanie Lomonaco, and Thomas E Wilson
Nucleic Acids Research, gkab597, doi: 10.1093/nar/gkab597
Recent years have seen considerable progress in understanding the most important regulatory decision in DNA double strand break (DSB) – the transition to 5’ resection – which commits a DSB to repair via homologous recombination. Most approaches to study DSB resection begin to monitor resection 100s of bp from the DSB end. This represents a significant experimental gap, since all modern models of resection invoke critical actions of Mre11 and other proteins within the first hundred base pairs of the DSB end. The authors of this paper addressed this gap by developing a novel method with low background for high throughput sequencing of single molecules undergoing DSB resection in yeast. They were able to observe critical resection events as they happened in vivo, leading to substantive mechanistic insights such as the distance from the DSB end where Mre11 makes a key incision, which nucleases extend this nick most efficiently, and the speed with which various processing events occur.