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U1 small nuclear RNA and spliceosomal introns in Euglena gracilis
U1 small nuclear RNA and spliceosomal introns in Euglena gracilis
5394
In the flagellated protozoon Euglena gracilis, characterized nuclear genes harbor atypical introns that usually are flanked by short repeats, adopt complex secondary structures in pre-mRNA, and do not obey the GT-AG rule of conventional cis-spliced introns. In the nuclear fibrillarin gene of E. gracilis, we have identified three spliceosomal-type introns that have GT-AG consensus borders. Furthermore, we have isolated a small RNA from E. gracilis and propose, on the basis of primary and secondary structure comparisons, that it is a homolog of U1 small nuclear RNA, an essential component of the cis-spliceosome in higher eukaryotes. Conserved sequences at the 5' splice sites of the fibrillarin introns can potentially base pair with Euglena U1 small nuclear RNA. Our observations demonstrate that spliceosomal GT-AG cis-splicing occurs in Euglena, in addition to the nonconventional cis-splicing and spliced leader trans-splicing previously recognized in this early diverging unicellular eukaryote.
Breckenridge DG, Watanabe Y, Greenwood SJ, Gray MW, Schnare MN
Proceedings of the National Academy of Sciences of the United States of America
1999-02-02 00:00
96
3
852-6
Animals,Base Pairing,Base Sequence,Conserved Sequence,DNA, Complementary,Euglena gracilis,Introns,Molecular Sequence Data,Nucleic Acid Conformation,Polymerase Chain Reaction,RNA, Protozoan,RNA, Small Nuclear,Spliceosomes,DNA, Complementary,RNA, Protozoan,RNA, Small Nuclear
Program in Evolutionary Biology, Canadian Institute for Advanced Research, Department of Biochemistry, Dalhousie University, Halifax, Nova Scotia B3H 4H7, Canada.
Proc. Natl. Acad. Sci. U.S.A.
0027-8424
0
False
9927657
