An intronic splicing enhancer binds U1 snRNPs to enhance splicing and select 5' splice sites.
Intronic G triplets are frequently located adjacent to 5' splice sites in vertebrate pre-mRNAs and have been correlated with splicing efficiency and specificity via a mechanism that activates upstream 5' splice sites in exons containing duplicated sites (26). Using an intron dependent upon G triplets for maximal activity and 5' splice site specificity, we determined that these elements bind U1 snRNPs via base pairing with U1 RNA. This interaction is novel in that it uses nucleotides 8 to 10 of U1 RNA and is independent of nucleotides 1 to 7. In vivo functionality of base pairing was documented by restoring activity and specificity to mutated G triplets through compensating U1 RNA mutations. We suggest that the G-rich region near vertebrate 5' splice sites promotes accurate splice site recognition by recruiting the U1 snRNP.
McCullough
A J
AJ
Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030, USA. andrewm@bcm.tmc.edu
Berget
S M
SM
D020029:Base Pairing; D001483:Base Sequence; D003432:Cross-Linking Reagents / Q000494:pharmacology; D004586:Electrophoresis; D004742:Enhancer Elements, Genetic / Q000235:genetics*; D005363:Ficusin / Q000494:pharmacology; D005914:Globins / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D007438:Introns / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins / Q000378:metabolism; D009690:Nucleic Acid Conformation; D010750:Phosphoproteins / Q000378:metabolism; D012313:RNA / Q000235:genetics / Q000378:metabolism; D022821:RNA Splice Sites / Q000235:genetics*; D012326:RNA Splicing / Q000235:genetics; D012342:RNA, Small Nuclear / Q000235:genetics* / Q000378:metabolism; D016601:RNA-Binding Proteins; D017412:Ribonucleoprotein, U1 Small Nuclear / Q000235:genetics* / Q000378:metabolism; D000068103:Serine-Arginine Splicing Factors; D014162:Transfection
D003432:Cross-Linking Reagents; D009687:Nuclear Proteins; D010750:Phosphoproteins; D022821:RNA Splice Sites; D012342:RNA, Small Nuclear; D016601:RNA-Binding Proteins; D017412:Ribonucleoprotein, U1 Small Nuclear; C405483:U1 small nuclear RNA; D000068103:Serine-Arginine Splicing Factors; D012313:RNA; D005914:Globins; D005363:Ficusin