Modulation of msl-2 5' splice site recognition by Sex-lethal.
The protein Sex-lethal (SXL) controls dosage compensation in Drosophila by inhibiting splicing and subsequently translation of male-specific-lethal-2 (msl-2) transcripts. We have previously shown that SXL blocks the binding of U2 auxiliary factor (U2AF) to the polypyrimidine (Py)-tract associated with the 3' splice site of the regulated intron. We now report that a second pyrimidine-rich sequence containing 11 consecutive uridines immediately downstream from the 5' splice site is required for efficient splicing inhibition by SXL. Psoralen-mediated crosslinking experiments suggest that SXL binding to this uridine-rich sequence inhibits recognition of the 5' splice site by U1 snRNP in HeLa nuclear extracts. We also show that SXL interferes with the binding of the protein TIA-1 to the uridine-rich stretch. Because TIA-1 binding to this sequence is necessary for U1 snRNP recruitment to msl-25' splice site and for splicing of this pre-mRNA, we propose that SXL antagonizes TIA-1 activity and thus prevents 5' splice site recognition by U1 snRNP. Taken together with previous data, we conclude that efficient retention of msl-2 intron involves inhibition of early recognition of both splice sites by SXL.
Förch
P
P
Gene Expression Programme, European Molecular Biology Laboratory, Heidelberg, Germany.
Merendino
L
L
Martínez
C
C
Valcárcel
J
J
D020121:5' Untranslated Regions; D001667:Binding, Competitive; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D006367:HeLa Cells; D006801:Humans; D007438:Introns; D008565:Membrane Proteins / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics*; D039102:Poly(A)-Binding Proteins; D011506:Proteins; D022821:RNA Splice Sites; D012326:RNA Splicing; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D017412:Ribonucleoprotein, U1 Small Nuclear / Q000378:metabolism; D000074019:T-Cell Intracellular Antigen-1; D014157:Transcription Factors / Q000235:genetics*
D020121:5' Untranslated Regions; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D008565:Membrane Proteins; D009687:Nuclear Proteins; D039102:Poly(A)-Binding Proteins; D011506:Proteins; D022821:RNA Splice Sites; D016601:RNA-Binding Proteins; D017412:Ribonucleoprotein, U1 Small Nuclear; C067777:Sxl protein, Drosophila; D000074019:T-Cell Intracellular Antigen-1; C071558:TIA1 protein, human; D014157:Transcription Factors; C094166:msl-2 protein, Drosophila