title: A magnesium ion core at the heart of a ribozyme domain.
abstract: Large ribozymes require divalent metal ions to fold. We show here that the tertiary structure of the Tetrahymena group I intron P4-P6 domain nucleates around a magnesium ion core. In the domain crystal structure, five magnesium ions bind in a three-helix junction at the centre of the molecule. Single atom changes in any one of four magnesium sites in this three-helix junction destroy folding of the entire 160-nucleotide P4-P6 domain. The magnesium ion core may be the RNA counterpart to the protein hydrophobic core, burying parts of the RNA molecule in the native structure.
authors.affiliation: Dept. of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520, USA.
authors.forename: J H
authors.initials: JH
authors.lastname: Cate
authors.forename: R L
authors.initials: RL
authors.lastname: Hanna
authors.forename: J A
authors.initials: JA
authors.lastname: Doudna
mesh_terms: D000818:Animals; D001665:Binding Sites; D018360:Crystallography, X-Ray; D007438:Introns; D008274:Magnesium / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D010710:Phosphates / Q000737:chemistry; D016337:RNA, Catalytic / Q000737:chemistry* / Q000378:metabolism*; D013768:Tetrahymena / Q000235:genetics; D013873:Thionucleotides / Q000737:chemistry
chemical_list: D010710:Phosphates; D016337:RNA, Catalytic; D013873:Thionucleotides; D008274:Magnesium