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PDBsum entry 1gpt
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References listed in PDB file
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Key reference
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Title
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Solution structure of gamma 1-H and gamma 1-P thionins from barley and wheat endosperm determined by 1h-Nmr: a structural motif common to toxic arthropod proteins.
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Authors
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M.Bruix,
M.A.Jiménez,
J.Santoro,
C.González,
F.J.Colilla,
E.Méndez,
M.Rico.
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Ref.
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Biochemistry, 1993,
32,
715-724.
[DOI no: ]
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PubMed id
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Abstract
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The complete assignment of the proton NMR spectra of the homologous gamma
1-hordothionin and gamma 1-purothionin (47 amino acids, 4 disulfide bridges)
from barley and wheat, respectively, has been performed by two-dimensional
sequence-specific methods. A total of 299 proton-proton distance constraints for
gamma 1-H and 285 for gamma 1-P derived from NOESY spectra have been used to
calculate the three-dimensional solution structures. Initial structures have
been generated by distance geometry methods and further refined by dynamical
simulated annealing calculations. Both proteins show identical secondary and
tertiary structure with a well-defined triple-stranded antiparallel beta-sheet
(residues 1-6, 31-34, and 39-47), an alpha-helix (residues 16-28), and the
corresponding connecting loops. Three disulfide bridges are located in the
hydrophobic core holding together the alpha-helix and the beta-sheet and forming
a cysteine-stabilized alpha-helical (CSH) motif. Moreover, a clustering of
positive charges is observed on the face of the beta-sheet opposite to the
helix. The three-dimensional structures of the gamma-thionins differ remarkably
from plant alpha- and beta-thionins and crambin. However, they show a higher
structural analogy with scorpion toxins and insect defensins which also present
the CSH motif.
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