title: The structure of human cleavage factor I(m) hints at functions beyond UGUA-specific RNA binding: a role in alternative polyadenylation and a potential link to 5' capping and splicing.
abstract: 3'-end cleavage and subsequent polyadenylation are critical steps in mRNA maturation. The precise location where cleavage occurs (referred to as poly(A) site) is determined by a tripartite mechanism in which a A(A/U)UAAA hexamer, GU rich downstream element and UGUA upstream element are recognized by the cleavage and polyadenylation factor (CPSF), cleavage stimulation factor (CstF) and cleavage factor I(m) (CFI(m)), respectively. CFI(m) is composed of a smaller 25 kDa subunit (CFI(m)25) and a larger 59, 68 or 72 kDa subunit. CFI(m)68 interacts with CFI(m)25 through its N-terminal RNA recognition motif (RRM). We recently solved the crystal structures of CFI(m)25 bound to RNA and of a complex of CFI(m)25, the RRM domain of CFI(m)68 and RNA. Our study illustrated the molecular basis for UGUA recognition by the CFI(m) complex, suggested a possible mechanism for CFI(m) mediated alternative polyadenylation, and revealed potential links between CFI(m) and other mRNA processing factors, such as the 20 kDa subunit of the cap binding protein (CBP20), and the splicing regulator U2AF65.
authors: Department of Microbiology and Molecular Genetics, The Markey Center for Molecular Genetics, University of Vermont, Burlington, VT, USA.
authors: Qin
authors: Q
authors: Yang
authors: Gregory M
authors: GM
authors: Gilmartin
authors: Sylvie
authors: S
authors: Doublié
mesh_terms: D001665:Binding Sites / Q000235:genetics; D039241:Cleavage Stimulation Factor / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D009687:Nuclear Proteins / Q000378:metabolism; D026723:Polyadenylation; D017433:Protein Structure, Secondary; D012315:RNA Caps / Q000235:genetics; D012323:RNA Processing, Post-Transcriptional; D022821:RNA Splice Sites / Q000235:genetics; D012326:RNA Splicing; D012333:RNA, Messenger / Q000378:metabolism*; D012261:Ribonucleoproteins / Q000378:metabolism; D000072668:Splicing Factor U2AF; D039221:mRNA Cleavage and Polyadenylation Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D039241:Cleavage Stimulation Factor; D009687:Nuclear Proteins; D012315:RNA Caps; D022821:RNA Splice Sites; D012333:RNA, Messenger; D012261:Ribonucleoproteins; D000072668:Splicing Factor U2AF; C000607494:U2AF2 protein, human; C450562:cleavage factor Im, human; D039221:mRNA Cleavage and Polyadenylation Factors