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Evidence for two active sites in the spliceosome provided by stereochemistry of pre-mRNA splicing.
Nature. 1993 Sep 23; 365(6444):364-8.Nat

Abstract

Excision of introns from nuclear precursors to messenger RNAs (pre-mRNAs) by the spliceosome requires two distinct phosphodiester transfer (transesterification) reactions: exchange of a 3'-5' for a 2'-5' bond in the first step (lariat formation) and exchange of one 3'-5' phosphodiester for another in the second step (exon ligation). We report here determination of the stereochemical course of each step using splicing substrates that contained a chiral phosphorothioate. This has provided strong evidence that both steps occur as single 'in-line' SN2 nucleophilic displacement reactions, analogous to the mechanism of group I self-splicing introns. Additionally, because both steps are strongly inhibited by the RP phosphorothioate diastereomer, but not by SP, the spliceosome probably shifts between two active sites in catalysis of the two steps. Chemical and stereochemical similarities suggest that the catalytic site for the second step of spliceosomal processing is related to that of group I self-splicing introns.

Authors+Show Affiliations

Center for Cancer Research, Massachusetts Institute of Technology, Cambridge 02139.No affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

8397340

Citation

Moore, M J., and P A. Sharp. "Evidence for Two Active Sites in the Spliceosome Provided By Stereochemistry of pre-mRNA Splicing." Nature, vol. 365, no. 6444, 1993, pp. 364-8.
Moore MJ, Sharp PA. Evidence for two active sites in the spliceosome provided by stereochemistry of pre-mRNA splicing. Nature. 1993;365(6444):364-8.
Moore, M. J., & Sharp, P. A. (1993). Evidence for two active sites in the spliceosome provided by stereochemistry of pre-mRNA splicing. Nature, 365(6444), 364-8.
Moore MJ, Sharp PA. Evidence for Two Active Sites in the Spliceosome Provided By Stereochemistry of pre-mRNA Splicing. Nature. 1993 Sep 23;365(6444):364-8. PubMed PMID: 8397340.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Evidence for two active sites in the spliceosome provided by stereochemistry of pre-mRNA splicing. AU - Moore,M J, AU - Sharp,P A, PY - 1993/9/23/pubmed PY - 1993/9/23/medline PY - 1993/9/23/entrez SP - 364 EP - 8 JF - Nature JO - Nature VL - 365 IS - 6444 N2 - Excision of introns from nuclear precursors to messenger RNAs (pre-mRNAs) by the spliceosome requires two distinct phosphodiester transfer (transesterification) reactions: exchange of a 3'-5' for a 2'-5' bond in the first step (lariat formation) and exchange of one 3'-5' phosphodiester for another in the second step (exon ligation). We report here determination of the stereochemical course of each step using splicing substrates that contained a chiral phosphorothioate. This has provided strong evidence that both steps occur as single 'in-line' SN2 nucleophilic displacement reactions, analogous to the mechanism of group I self-splicing introns. Additionally, because both steps are strongly inhibited by the RP phosphorothioate diastereomer, but not by SP, the spliceosome probably shifts between two active sites in catalysis of the two steps. Chemical and stereochemical similarities suggest that the catalytic site for the second step of spliceosomal processing is related to that of group I self-splicing introns. SN - 0028-0836 UR - https://www.unboundmedicine.com/medline/citation/8397340/Evidence_for_two_active_sites_in_the_spliceosome_provided_by_stereochemistry_of_pre_mRNA_splicing_ DB - PRIME DP - Unbound Medicine ER -