BuTT-Seq: a new method for facile profiling of transcription

A wide range of sequencing methods have been developed to assess nascent RNA transcription and resolve the single-nucleotide position of RNA polymerase genome-wide. These techniques are often burdened with high input material requirements and lengthy protocols. We leveraged the template-switching properties of thermostable group II intron reverse transcriptase (TGIRT) and developed BuTT-Seq (BUlk analysis of nascent Transcript Termini sequencing), which can produce libraries from purified nascent RNA in 6 hours and from as few as 10,000 cells - an improvement of at least 25-fold over existing techniques. BuTT-Seq shows that inhibition of the superelongation complex (SEC) causes promoter-proximal pausing to move upstream in a fashion correlated with subnucleosomal fragments. To address transcriptional regulation in a tissue, BuTT-Seq was used to measure the circadian regulation of transcription from fly heads. All the results indicate that BuTT-Seq is a simple and powerful technique to analyze transcription at a high level of resolution. ### Competing Interest Statement The authors have declared no competing interest.