Splicing of a divergent subclass of AT-AC introns requires the major spliceosomal snRNAs

Wu, Q., Krainer, A. R. (June 1997) Splicing of a divergent subclass of AT-AC introns requires the major spliceosomal snRNAs. RNA, 3 (6). pp. 586-601. ISSN 13558382 (ISSN)

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URL: http://www.ncbi.nlm.nih.gov/pubmed/9174094

Abstract

AT-AC introns constitute a minor class of eukaryotic pre-mRNA introns, characterized by 5'-AT and AC-3' boundaries, in contrast to the 5'-GT and AG-3' boundaries of the much more prevalent conventional introns. In addition to the AT-AC borders, most known AT-AC introns have highly conserved 5' splice site and branch site sequence elements of 7-8 nt. Intron 6 of the nucleolar P120 gene and intron 2 of the SCN4A voltage-gated skeletal muscle sodium channel are AT-AC introns that have been shown recently to be processed via a unique splicing pathway involving several minor U snRNAs. Interestingly, intron 21 of the same SCN4A gene and the corresponding intron 25 of the SCN5A cardiac muscle sodium channel gene also have 5'-AT and AC-3' boundaries, but they have divergent 5' splice site and presumptive branch site sequences. Here, we report the accurate in vitro processing of these two divergent AT-AC introns and show that they belong to a functionally distinct subclass of AT-AC introns. Splicing of these introns does not require U12, U4atac, and U6atac snRNAs, but instead requires the major spliceosomal snRNAs U1, U2, U4, U5, and U6. Previous studies showed that G --> A mutation at the first position and G --> C mutation at the last position of a conventional yeast or mammalian GT-AG intron suppress each other in vivo, suggesting that the first and last bases participate in an essential non-Watson-Crick interaction. Our results show that such introns, hereafter termed AT-AC II introns, occur naturally and are spliced by a mechanism distinct from that responsible for processing of the apparently more common AT-AC I introns.

Item Type: Paper
Uncontrolled Keywords: divergent AT-AC introns in vitro splicing pre-mRNA splicing skeletal and cardiac muscle sodium channel small nuclear ribonucleoproteins sodium-channel gene cartilage matrix protein messenger-rna precursors site selection genomic structure skeletal-muscle u1 snrnp u6 snrna last nucleotides
Subjects: bioinformatics > genomics and proteomics > genetics & nucleic acid processing > DNA, RNA structure, function, modification
bioinformatics > genomics and proteomics > genetics & nucleic acid processing
bioinformatics > genomics and proteomics > genetics & nucleic acid processing > DNA, RNA structure, function, modification > introns > intron splicing
bioinformatics > genomics and proteomics > genetics & nucleic acid processing > DNA, RNA structure, function, modification > introns
bioinformatics > genomics and proteomics > genetics & nucleic acid processing > DNA, RNA structure, function, modification > pre-mRNA
bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types
bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types > spliceosome complex
CSHL Authors:
Communities: CSHL labs > Krainer lab
Depositing User: Matt Covey
Date: June 1997
Date Deposited: 11 Dec 2013 15:43
Last Modified: 11 Dec 2013 15:43
PMCID: PMC1369508
Related URLs:
URI: http://repository.cshl.edu/id/eprint/28937

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