DSSR-PyMOL cartoon-block schematics: PDB entry 1lmv

PDB-id

1lmv; DSSR-derived features in text and JSON formats

Class

RNA

Method

NMR

Summary

Solution structure of the unmodified u2 snrna-intron branch site helix from s. cerevisiae

Reference

Newby MI, Greenbaum NL (2002): "Sculpting of the Spliceosomal Branch Site Recognition Motif by a Conserved Pseudouridine." Nat.Struct.Biol., 9, 958-965. doi: 10.1038/nsb873.

Abstract

Pairing of a consensus sequence of the precursor (pre)-mRNA intron with a short region of the U2 small nuclear (sn)RNA during assembly of the eukaryotic spliceosome results in formation of a complementary helix of seven base pairs with a single unpaired adenosine residue. The 2' OH of this adenosine, called the branch site, brings about nucleophilic attack at the pre-mRNA 5' splice site in the first step of splicing. Another feature of this pairing is the phylogenetic conservation of a pseudouridine (psi) residue in U2 snRNA nearly opposite the branch site. We show that the presence of this psi in the pre-mRNA branch-site helix of Saccharomyces cerevisiae induces a dramatically altered architectural landscape compared with that of its unmodified counterpart. The psi-induced structure places the nucleophile in an accessible position for the first step of splicing.