, which lacks canonical transcription-coupled repair proteins, performs transcription-coupled repair.

Previous work with the classic T4 endonuclease V digestion of DNA from irradiated cells followed by Southern hybridization led to the conclusion that lacks transcription-coupled repair (TCR). This conclusion was reinforced by the Genome Project, which revealed that lacks Cockayne syndrome WD repeat protein (CSA), CSB, or UV-stimulated scaffold protein A (UVSSA) homologs, whose orthologs are present in eukaryotes ranging from to humans that carry out TCR. A recently developed excision assay and the excision repair-sequencing (XR-Seq) method have enabled genome-wide analysis of nucleotide excision repair in various organisms at single-nucleotide resolution and in a strand-specific manner. Using these methods, we have discovered that S2 cells carry out robust TCR comparable with that observed in mammalian cells. Our findings provide critical new insights into the mechanisms of TCR among various different species.