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NMR structure of a KlbA intein precursor from Methanococcus jannaschii
Author(s) -
Johnson Margaret A.,
Southworth Maurice W.,
Herrmann Torsten,
Brace Lear,
Perler Francine B.,
Wüthrich Kurt
Publication year - 2007
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1110/ps.072816707
Subject(s) - intein , methanococcus , protein splicing , antiparallel (mathematics) , stereochemistry , peptide bond , chemistry , residue (chemistry) , peptide , rna splicing , biochemistry , gene , rna , physics , escherichia coli , quantum mechanics , magnetic field
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 β‐strands are arranged in a complex fold that includes four β‐hairpins and an antiparallel β‐ribbon, and there is one α‐helix, which is packed against the β‐ribbon, and one turn of 3 10 ‐helix in the loop between the β‐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.