Chimeric human CstF-77/Drosophila Suppressor of forked proteins rescue suppressor of forked mutant lethality and mRNA 3' end processing in Drosophila.
The Suppressor of forked [Su(f)] protein is the Drosophila homologue of CstF-77, a subunit of human cleavage stimulation factor (CstF) that is required for the first step of the mRNA 3' end processing reaction in vitro. We have addressed directly the role of su(f) in the mRNA 3' end processing reaction in vivo. We show that su(f) is required for the cleavage of pre-mRNA during mRNA 3' end formation. Analysis of the functional complementation between Su(f) and CstF-77 shows that most of the Drosophila protein (85%) can be exchanged for the human protein to produce chimeric CstF-77/Su(f) proteins that rescue lethality and cleavage defect during mRNA 3' end formation in su(f) mutants. Interestingly, we show that a domain in human CstF-77 is limiting for the rescue and that this domain is not able to reproduce protein interactions with the CstF subunits of Drosophila. We also show that chimeric CstF-77/Su(f) proteins that rescue lethality of su(f) mutants cannot restore utilization of a regulated poly(A) site in Drosophila. Taken together, these results demonstrate that CstF-77 and Su(f) have the same function in mRNA 3' end formation in vivo, but that these two proteins are not interchangeable for regulation of poly(A) site utilization.
Benoit
Béatrice
B
Génétique du Développement de la Drosophile, Institut de Génétique Humaine, 141 Rue de la Cardonille, 34396 Montpellier Cedex 5, France.
Juge
François
F
Iral
Florence
F
Audibert
Agnès
A
Simonelig
Martine
M
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D018076:DNA, Complementary; D029721:Drosophila Proteins; D004331:Drosophila melanogaster; D006801:Humans; D019476:Insect Proteins / Q000235:genetics / Q000502:physiology*; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009687:Nuclear Proteins; D011061:Poly A; D012322:RNA Precursors; D012323:RNA Processing, Post-Transcriptional; D016601:RNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000502:physiology; D017386:Sequence Homology, Amino Acid; D039221:mRNA Cleavage and Polyadenylation Factors
D018076:DNA, Complementary; D029721:Drosophila Proteins; D019476:Insect Proteins; D009687:Nuclear Proteins; D012322:RNA Precursors; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D039221:mRNA Cleavage and Polyadenylation Factors; C079745:su(f) protein, Drosophila; D011061:Poly A