Open AccessSpeciation of a group I intron into a lariat capping ribozyme
Author(s) -
Mélanie Meyer,
Henrik Nielsen,
Vincent Oliéric,
Pierre Roblin,
Steinar Johansen,
Éric Westhof,
Benoı̂t Masquida
Publication year - 2014
Publication title -
proceedings of the national academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.1322248111
Subject(s) - ribozyme , hairpin ribozyme , homing endonuclease , mammalian cpeb3 ribozyme , vs ribozyme , biology , group i catalytic intron , rna , intron , ligase ribozyme , stereochemistry , chemistry , biochemistry , gene
The lariat-capping (LC) ribozyme is a natural ribozyme isolated from eukaryotic microorganisms. Despite apparent structural similarity to group I introns, the LC ribozyme catalyzes cleavage by a 2',5' branching reaction, leaving the 3' product with a 3-nt lariat cap that functionally substitutes for a conventional mRNA cap in the downstream pre-mRNA encoding a homing endonuclease. We describe the crystal structures of the precleavage and postcleavage LC ribozymes, which suggest that structural features inherited from group I ribozymes have undergone speciation due to profound changes in molecular selection pressure, ultimately giving rise to an original branching ribozyme family. The structures elucidate the role of key elements that regulate the activity of the LC ribozyme by conformational switching and suggest a mechanism by which the signal for branching is transmitted to the catalytic core. The structures also show how conserved interactions twist residues, forming the lariat to join chemical groups involved in branching.
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