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Activation of Transcription‐Coupled 5′‐RNA Capping by TFIIH
Author(s) -
NoeGonzalez Melvin,
Conaway Joan,
Conaway Ronald
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.907.1
Subject(s) - transcription factor ii h , rna polymerase ii , rna polymerase ii holoenzyme , transcription (linguistics) , transcription factor ii a , transcription factor ii f , transcription factor ii b , general transcription factor , microbiology and biotechnology , transcription preinitiation complex , biology , chemistry , transcriptional regulation , rna , genetics , transcription factor , promoter , nucleotide excision repair , dna , rna polymerase , dna repair , gene expression , gene , linguistics , philosophy
Transcription is coupled in time and space to various mRNA processing events including 5′ capping, splicing, and polyadenylation. Capping of the 5′ end of pre‐mRNA, the first detectable mRNA processing event, is thought to occur by the time the transcript is only 25–30 nucleotides long and correlates with hyperphosphorylation of the C‐terminal domain (CTD) of transcribing Pol II. Notably, previous studies have shown that capping is over 100‐fold more efficient when coupled to Pol II transcription. Here we exploit a highly purified, reconstituted Pol II transcription system to investigate the mechanism of co‐transcriptional capping. We present direct evidence that TFIIH functions as a potent activator of co‐transcriptional capping in this system. The TFIIH‐associated CAK protein kinase most likely contributes to TFIIH action in transcription‐coupled capping in light of evidence (i) that CAK inhibitors, H8 and THZ1, inhibit TFIIH function and (ii) that recombinant CAK can at least partially replace TFIIH. Finally, we use DNA:RNA scaffolds to show that capping of transcripts in artificial Pol II elongation complexes also requires TFIIH and its CAK kinase in the absence of other general transcription factors. Taken together, these data support the model that TFIIH‐dependent phosphorylation, most likely of the Pol II CTD, plays an integral role in transcription‐coupled RNA capping.