title: NMR structure of a KlbA intein precursor from Methanococcus jannaschii.
abstract: Certain proteins of unicellular organisms are translated as precursor polypeptides containing inteins (intervening proteins), which are domains capable of performing protein splicing. These domains, in conjunction with a single residue following the intein, catalyze their own excision from the surrounding protein (extein) in a multistep reaction involving the cleavage of two intein-extein peptide bonds and the formation of a new peptide bond that ligates the two exteins to yield the mature protein. We report here the solution NMR structure of a 186-residue precursor of the KlbA intein from Methanococcus jannaschii, comprising the intein together with N- and C-extein segments of 7 and 11 residues, respectively. The intein is shown to adopt a single, well-defined globular domain, representing a HINT (Hedgehog/Intein)-type topology. Fourteen beta-strands are arranged in a complex fold that includes four beta-hairpins and an antiparallel beta-ribbon, and there is one alpha-helix, which is packed against the beta-ribbon, and one turn of 3(10)-helix in the loop between the beta-strands 8 and 9. The two extein segments show increased disorder, and form only minimal nonbonding contacts with the intein domain. Structure-based mutation experiments resulted in a proposal for functional roles of individual residues in the intein catalytic mechanism.
authors.affiliation: The Scripps Research Institute, Department of Molecular Biology, La Jolla, CA 92037, USA.
authors.forename: Margaret A
authors.initials: MA
authors.lastname: Johnson
authors.forename: Maurice W
authors.initials: MW
authors.lastname: Southworth
authors.forename: Torsten
authors.initials: T
authors.lastname: Herrmann
authors.forename: Lear
authors.initials: L
authors.lastname: Brace
authors.forename: Francine B
authors.initials: FB
authors.lastname: Perler
authors.forename: Kurt
authors.initials: K
authors.lastname: Wüthrich
mesh_terms: D000595:Amino Acid Sequence; D019843:Archaeal Proteins / Q000737:chemistry* / Q000235:genetics; D047668:Inteins; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D017015:Methanococcales / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011498:Protein Precursors / Q000737:chemistry* / Q000235:genetics; D019154:Protein Splicing; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid
chemical_list: D019843:Archaeal Proteins; D011498:Protein Precursors