3bo3
A relaxed active site following exon ligation by a group I intronA relaxed active site following exon ligation by a group I intron
Structural highlights
Function[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.[1] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedDuring RNA maturation, the group I intron promotes two sequential phosphorotransfer reactions resulting in exon ligation and intron release. Here, we report the crystal structure of the intron in complex with spliced exons and two additional structures that examine the role of active-site metal ions during the second step of RNA splicing. These structures reveal a relaxed active site, in which direct metal coordination by the exons is lost after ligation, while other tertiary interactions are retained between the exon and the intron. Consistent with these structural observations, kinetic and thermodynamic measurements show that the scissile phosphate makes direct contact with metals in the ground state before exon ligation and in the transition state, but not after exon ligation. Despite no direct exonic interactions and even in the absence of the scissile phosphate, two metal ions remain bound within the active site. Together, these data suggest that release of the ligated exons from the intron is preceded by a change in substrate-metal coordination before tertiary hydrogen bonding contacts to the exons are broken. A relaxed active site after exon ligation by the group I intron.,Lipchock SV, Strobel SA Proc Natl Acad Sci U S A. 2008 Apr 15;105(15):5699-704. Epub 2008 Apr 11. PMID:18408159[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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