KAS-Analyzer: an integrated toolkit for exploring KAS-seq data

Kethoxal-assisted ssDNA sequencing (KAS-seq) is gaining popularity as a robust and effective approach to study the dynamics of transcriptionally engaged RNA polymerases through profiling of genome-wide single-stranded DNA (ssDNA). Its latest variant, spKAS-seq, a strand-specific version of KAS-seq, has been developed to map genome-wide R-loop structures by detecting imbalances of ssDNA on two strands. However, user-friendly, open-source, and specific bioinformatic analyzer for KAS-seq data are still lacking. Here we present KAS-Analyzer as a flexible and integrated toolkit to facilitate the analysis and interpretation of KAS-seq data. KAS-Analyzer can perform standard analyses such as quality control, read alignment, and differential RNA polymerase activity analysis. In addition, KAS-Analyzer introduces many novel features, including, but not limited to: calculation of transcriptional indexes, identification of single-stranded transcribing enhancers, and high-resolution mapping of R-loops. We use benchmark datasets to demonstrate that KAS-Analyzer provides a powerful framework to study transient transcriptional regulatory programs. KAS-Analyzer is available at https://github.com/Ruitulyu/KAS-Analyzer. Overall design: We perfomed KAS-seq and spKAS-seq in several popular human cell lines and UVB radiation treated NHEK cells.