4FAQ: Structure Of Oceanobacillus Iheyensis Group Ii Intron In The Presence Of K+, Ca2+ And 5'-Exon

Group II introns are self-splicing ribozymes that share a reaction mechanism and a common ancestor with the eukaryotic spliceosome, thereby providing a model system for understanding the chemistry of pre-mRNA splicing. Here we report 14 crystal structures of a group II intron at different stages of catalysis. We provide a detailed mechanism for the first step of splicing, we describe a reversible conformational change between the first and the second steps of splicing, and we present the ligand-free intron structure after splicing in an active state that corresponds to the retrotransposable form of the intron. During each reaction, the reactants are aligned and activated by a heteronuclear four-metal-ion center that contains a metal cluster and obligate monovalent cations, and they adopt a structural arrangement similar to that of protein endonucleases. Based on our data, we propose a model for the splicing cycle and show that it is applicable to the eukaryotic spliceosome.
PDB ID: 4FAQDownload
MMDB ID: 105058
PDB Deposition Date: 2012/5/22
Updated in MMDB: 2012/11
Experimental Method:
x-ray diffraction
Resolution: 3.11  Å
Source Organism:
Biological Unit for 4FAQ: monomeric; determined by author and by software (PISA)
Molecular Components in 4FAQ
Label Count Molecule
Nucleotide(1 molecule)
Group IIC Intron
Molecule annotation
Chemicals (52 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB