title: Crystal structure of a self-spliced group II intron.
abstract: Group II introns are self-splicing ribozymes that catalyze their own excision from precursor transcripts and insertion into new genetic locations. Here we report the crystal structure of an intact, self-spliced group II intron from Oceanobacillus iheyensis at 3.1 angstrom resolution. An extensive network of tertiary interactions facilitates the ordered packing of intron subdomains around a ribozyme core that includes catalytic domain V. The bulge of domain V adopts an unusual helical structure that is located adjacent to a major groove triple helix (catalytic triplex). The bulge and catalytic triplex jointly coordinate two divalent metal ions in a configuration that is consistent with a two-metal ion mechanism for catalysis. Structural and functional analogies support the hypothesis that group II introns and the spliceosome share a common ancestor.
authors.affiliation: Department of Molecular Biophysics and Biochemistry, Yale University, 266 Whitney Avenue, Bass Building, New Haven, CT 06511, USA. navtej.toor@yale.edu
authors.forename: Navtej
authors.initials: N
authors.lastname: Toor
authors.forename: Kevin S
authors.initials: KS
authors.lastname: Keating
authors.forename: Sean D
authors.initials: SD
authors.lastname: Taylor
authors.forename: Anna Marie
authors.initials: AM
authors.lastname: Pyle
mesh_terms: D000494:Allosteric Regulation; D001406:Bacillaceae / Q000737:chemistry / Q000235:genetics*; D020029:Base Pairing; D001665:Binding Sites; D002384:Catalysis; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D019143:Evolution, Molecular; D007438:Introns; D008024:Ligands; D008274:Magnesium / Q000737:chemistry; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D010802:Phylogeny; D012326:RNA Splicing; D012329:RNA, Bacterial / Q000737:chemistry* / Q000378:metabolism; D016337:RNA, Catalytic / Q000737:chemistry* / Q000378:metabolism; D017381:Spliceosomes / Q000737:chemistry / Q000378:metabolism
chemical_list: D008024:Ligands; D012329:RNA, Bacterial; D016337:RNA, Catalytic; D008274:Magnesium