Crystal structure of a hairpin ribozyme in the catalytically-active conformation
[SNRPA_HUMAN] Binds stem loop II of U1 snRNA. It is the first snRNP to interact with pre-mRNA. This interaction is required for the subsequent binding of U2 snRNP and the U4/U6/U5 tri-snRNP. In a snRNP-free form (SF-A) may be involved in coupled pre-mRNA splicing and polyadenylation process. Binds preferentially to the 5'-UGCAC-3' motif in vitro.
Publication Abstract from PubMed
The hairpin ribozyme catalyses sequence-specific cleavage of RNA. The active site of this natural RNA results from the docking of two irregular helices: stems A and B. One strand of stem A harbours the scissile bond. The 2.4 A resolution structure of a hairpin ribozyme-inhibitor complex reveals that the ribozyme aligns the 2'-OH nucleophile and the 5'-oxo leaving group by twisting apart the nucleotides that flank the scissile phosphate. The base of the nucleotide preceding the cleavage site is stacked within stem A; the next nucleotide, a conserved guanine, is extruded from stem A and accommodated by a highly complementary pocket in the minor groove of stem B. Metal ions are absent from the active site. The bases of four conserved purines are positioned potentially to serve as acid-base catalysts. This is the first structure determination of a fully assembled ribozyme active site that catalyses a phosphodiester cleavage without recourse to metal ions.
Crystal structure of a hairpin ribozyme-inhibitor complex with implications for catalysis.,Rupert PB, Ferre-D'Amare AR Nature. 2001 Apr 12;410(6830):780-6. PMID:11298439
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.