5J02

Structure of the lariat form of a chimeric derivative of the Oceanobacillus iheyensis group II intron in the presence of NH4+, MG2+ and an inactive 5' exon.

Summary for 5J02

• Entry DOI: 10.2210/pdb5j02/pdb
• Descriptor: GROUP II INTRON LARIAT, 5' EXON ANALOG (5'-R(*CP*UP*GP*UP*UP*AP*(5MU))-3'), MAGNESIUM ION, ... (5 entities in total)
• Functional Keywords: group ii intron, lariat, 2'-5' phosphodiester bond, ribozyme, rna catalysis, self-splicing, rna
• Biological source: Oceanobacillus iheyensis; More
• Total number of polymer chains: 2
• Total formula weight: 139176.33

Authors

Costa, M.,Walbott, H.,Monachello, D.,Westhof, E.,Michel, F. (deposition date: 2016-03-26, release date: 2016-12-14, Last modification date: 2024-01-10)

Primary citation

Costa, M.,Walbott, H.,Monachello, D.,Westhof, E.,Michel, F.
Crystal structures of a group II intron lariat primed for reverse splicing.
Science, 354:-, 2016

PubMed Abstract: The 2'-5' branch of nuclear premessenger introns is believed to have been inherited from self-splicing group II introns, which are retrotransposons of bacterial origin. Our crystal structures at 3.4 and 3.5 angstrom of an excised group II intron in branched ("lariat") form show that the 2'-5' branch organizes a network of active-site tertiary interactions that position the intron terminal 3'-hydroxyl group into a configuration poised to initiate reverse splicing, the first step in retrotransposition. Moreover, the branchpoint and flanking helices must undergo a base-pairing switch after branch formation. A group II-based model of the active site of the nuclear splicing machinery (the spliceosome) is proposed. The crucial role of the lariat conformation in active-site assembly and catalysis explains its prevalence in modern splicing.

PubMed: 27934709
DOI: 10.1126/science.aaf9258

Experimental method

X-RAY DIFFRACTION (3.493 Å)