Illuminating genome repair by photolyase

Exposure to the ultraviolet (UV) spectrum of sunlight poses a threat to terrestrial species. Nearly all species possess the nucleotide excision repair (NER) machinery, which can repair the helix-distorting DNA lesions induced by UV light. However, many species also have photolyase enzymes, which use near-UV and visible wavelengths of sunlight to directly reverse major classes of UV photoproducts. In eukaryotic cells, both of these repair pathways must efficiently locate and repair UV photoproducts present in chromatin. While genome-wide damage mapping methods have been used to extensively characterize how chromatin and ongoing transcription impact NER, much less is known about how photolyase enzymes navigate these obstacles to repair UV damage. Here, we highlight a recent article from our laboratory that used genome-wide sequencing methods to characterize how yeast photolyase repairs UV damage, both in NER-proficient and -deficient cells, and prevents UV-induced mutations.