mRNA capping enzyme is recruited to the transcription complex by phosphorylation of the RNA polymerase II carboxy-terminal domain.
Capping of mRNA occurs shortly after transcription initiation, preceding other mRNA processing events such as mRNA splicing and polyadenylation. To determine the mechanism of coupling between transcription and capping, we tested for a physical interaction between capping enzyme and the transcription machinery. Capping enzyme is not stably associated with basal transcription factors or the RNA polymerase II (Pol II) holoenzyme. However, capping enzyme can directly and specifically interact with the phosphorylated form of the RNA polymerase carboxy-terminal domain (CTD). This association occurs in the context of the transcription initiation complex and is blocked by the CTD-kinase inhibitor H8. Furthermore, conditional truncation mutants of the Pol II CTD are lethal when combined with a capping enzyme mutant. Our results provide in vitro and in vivo evidence that capping enzyme is recruited to the transcription complex via phosphorylation of the RNA polymerase CTD.
Cho
E J
EJ
Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, USA.
Takagi
T
T
Moore
C R
CR
Buratowski
S
S
D001665:Binding Sites; D009713:Nucleotidyltransferases / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D012319:RNA Polymerase II / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D051758:Transcription Factor TFIIH; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D019473:Transcription Factors, TFII; D014158:Transcription, Genetic; D000098556:mRNA Guanylyltransferases
D012333:RNA, Messenger; D011994:Recombinant Proteins; D014157:Transcription Factors; D019473:Transcription Factors, TFII; D051758:Transcription Factor TFIIH; D009713:Nucleotidyltransferases; D012319:RNA Polymerase II; D000098556:mRNA Guanylyltransferases