title: The G-rich auxiliary downstream element has distinct sequence and position requirements and mediates efficient 3' end pre-mRNA processing through a trans-acting factor.
abstract: A downstream G-rich sequence (GRS), GGGGGAGGUGUGGG, has been previously shown to influence the efficiency of 3' end processing of the SV40 late polyadenylation signal. We have now defined several important parameters for GRS-mediated polyadenylation. The ability of the GRS to influence 3' end processing efficiency was sensitive to individual and multiple point mutations within the element, as well as the position of the element in the downstream region. Competition analysis indicated that the GRS functioned through a titratable trans-acting factor. The GRS-specific DSEF-1 protein was found to be bound to the same population of RNAs as the 64 kDa protein of the general polyadenylation factor CstF, indicating that DSEF-1 is associated with RNA substrates undergoing 3' end processing. Furthermore, an association was obtained between the relative strength of DSEF-1 protein binding to GRS variants and the relative ability of the GRS variants to mediate efficient cleavage in vitro. Finally, mutations in the GRS affected the efficiency of cross-linking of the 64 kDa protein of CstF. These data define a novel class of auxiliary downstream element and suggest an important role for DSEF-1 in 3' end processing.
authors.affiliation: UMD-New Jersey Medical School, Department of Microbiology and Molecular Genetics, Newark 07103, USA.
authors.forename: P S
authors.initials: PS
authors.lastname: Bagga
authors.forename: L P
authors.initials: LP
authors.lastname: Ford
authors.forename: F
authors.initials: F
authors.lastname: Chen
authors.forename: J
authors.initials: J
authors.lastname: Wilusz
mesh_terms: D001483:Base Sequence; D017353:Gene Deletion; D006147:Guanine / Q000378:metabolism; D008969:Molecular Sequence Data; D039102:Poly(A)-Binding Proteins; D012322:RNA Precursors / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D016601:RNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D017421:Sequence Analysis; D013539:Simian virus 40 / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics*
chemical_list: C088356:GRSF1 protein, human; D039102:Poly(A)-Binding Proteins; D012322:RNA Precursors; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D015534:Trans-Activators; D006147:Guanine