Role of the C-Terminal Domain of RNA Polymerase II in U2 snRNA Transcription and 3′ Processing

AUTOR(ES)

Jacobs, Erica Y.

FONTE

American Society for Microbiology

RESUMO

U small nuclear RNAs (snRNAs) and mRNAs are both transcribed by RNA polymerase II (Pol II), but the snRNAs have unusual TATA-less promoters and are neither spliced nor polyadenylated; instead, 3′ processing is directed by a highly conserved 3′ end formation signal that requires initiation from an snRNA promoter. Here we show that the C-terminal domain (CTD) of Pol II is required for efficient U2 snRNA transcription, as it is for mRNA transcription. However, CTD kinase inhibitors, such as 5,6-dichloro-1-β-d-ribofuranosylbenzimidazole (DRB) and 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H7), that block mRNA elongation do not affect U2 transcription, although 3′ processing of the U2 primary transcript is impaired. We show further that U2 transcription is preferentially inhibited by low doses of UV irradiation or actinomycin D, which induce CTD kinase activity, and that UV inhibition can be rescued by treatment with DRB or H7. We propose that Pol II complexes transcribing snRNAs and mRNAs have distinct CTD phosphorylation patterns. mRNA promoters recruit factors including kinases that hyperphosphorylate the CTD, and the CTD in turn recruits proteins needed for mRNA splicing and polyadenylation. We predict that snRNA promoters recruit factors including a CTD kinase(s) whose snRNA-specific phosphorylation pattern recruits factors required for promoter-coupled 3′ end formation.

Documentos Relacionados

• The C-terminal domain of pol II and a DRB-sensitive kinase are required for 3′ processing of U2 snRNA
• Xenopus laevis U2 snRNA genes: tandemly repeated transcription units sharing 5' and 3' flanking homology with other RNA polymerase II transcribed genes
• Xenopus laevis U2 snRNA genes: tandemly repeated transcription units sharing 5' and 3' flanking homology with other RNA polymerase II transcribed genes.
• Elements required for transcription initiation of the human U2 snRNA gene coincide with elements required for snRNA 3' end formation.
• Requirements of the RNA Polymerase II C-Terminal Domain for Reconstituting Pre-mRNA 3′ Cleavage