Transient transcriptome sequencing (TT-Seq) and 5'P-Seq of ATP-analog sensitive Kin28 budding yeast

Inhibition of Kin28/CDK7, the kinase subunit of TFIIH, leads to defects in transcription of protein-coding genes. Despite a severe reduction in nascent RNA synthesis, the majority of mRNAs retain their steady-state level upon inhibition. In this study, we examined the determinants of mRNA stability in cells experiencing transcriptional crisis via irreversible chemical inhibition of Kin28. We discovered that the inhibited Kin28 transcriptome resembles the transcriptome of cells treated with an inhibitor of protein synthesis. Indeed, inhibition of Kin28 induces a coordinated decrease in translation and an increase in P-body formation. Unexpectedly, integrated stress response effectors do not trigger the observed proteostasis and ribostasis. Rather, mRNAs that are buffered from degradation display a preference for Ski2 over Nab2 and are differentially sensitive to the 5′-exonuclease Xrn1. These findings reveal that a nuclear kinase, well-known for its role in early stages of RNA synthesis, orchestrates multiple molecular processes in different cellular compartments.