Involvement of yeast carboxy-terminal domain kinase I (CTDK-I) in transcription elongation in vivo

Yeast cells lacking transcription elongation factor genes such as PPR2 (TFI IS) and ELF (Elongator) are viable and show deleterious phenotypes only whe n transcription is rendered less effective by RNA polymerase mutations or b y decreasing nucleotide pools. Here we demonstrate that deletion of the CTK 1 gene, encoding the kinase subunit of RNA polymerase LI carboxy-terminal d omain kinase I (CTDK-I), is synthetically lethal when combined with deletio n of PPR2 or ELF genes. The inviability of ctk1 elp3 double mutants can be rescued by expression of an Elp3 mutant that has retained its ability to fo rm the Elongator complex but has severely diminished histone acetyltransfer ase activity, suggesting that the functional overlap between CTDK-I and Elo ngator is in assembly of RNA polymerase II elongation complexes. Our result s suggest that CTDK-I plays an important role in transcriptional elongation in vivo, possibly by creating a form of RNA polymerase that is less prone to transcriptional arrest. (C) 2001 Elsevier Science B.V. All rights reserv ed.