The poly(A)-dependent transcriptional pause is mediated by CPSF acting on the body of the polymerase.
Eukaryotic poly(A) signals direct mRNA 3'-end processing and also pausing and termination of transcription. We show that pausing and termination require the processing factor CPSF, which binds the AAUAAA hexamer of the mammalian poly(A) signal. Pausing does not require the RNA polymerase II C-terminal domain (CTD) or the cleavage stimulation factor, CstF, that binds the CTD. Pull-down experiments show that CPSF binds, principally through its 30-kDa subunit, to the body of the polymerase. CPSF can also bind CstF, but this seems to be mutually exclusive with polymerase binding. We suggest that CPSF, while binding the body of the polymerase, scans for hexamers in the extruding RNA. Any encounter with a hexamer triggers pausing. If the hexamer is part of a functional poly(A) signal, CstF is recruited and binds CPSF, causing it to release the polymerase body and move (with CstF) to the CTD.
Nag
Anita
A
Department of Chemistry and Biochemistry and the Molecular Biology Institute, University of California at Los Angeles, Los Angeles, California 90095-1569, USA.
Narsinh
Kazim
K
Martinson
Harold G
HG
D000818:Animals; D002460:Cell Line; D039223:Cleavage And Polyadenylation Specificity Factor / Q000037:antagonists & inhibitors / Q000378:metabolism*; D039241:Cleavage Stimulation Factor / Q000378:metabolism; D012321:DNA-Directed RNA Polymerases / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D011061:Poly A / Q000378:metabolism*; D039104:RNA 3' Polyadenylation Signals; D012333:RNA, Messenger / Q000737:chemistry / Q000378:metabolism; D017384:Sequence Deletion; D014158:Transcription, Genetic
D039223:Cleavage And Polyadenylation Specificity Factor; D039241:Cleavage Stimulation Factor; D012333:RNA, Messenger; D011061:Poly A; D012321:DNA-Directed RNA Polymerases