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ANS complex of St John's wort PR-10 protein with 28 copies in the asymmetric unit: a fiendish combination of pseudosymmetry with tetartohedral twinning.

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Sliwiak, Joanna 
Dauter, Zbigniew 
Kowiel, Marcin 
McCoy, Airlie J 
Read, Randy J 


Hyp-1, a pathogenesis-related class 10 (PR-10) protein from St John's wort (Hypericum perforatum), was crystallized in complex with the fluorescent probe 8-anilino-1-naphthalene sulfonate (ANS). The highly pseudosymmetric crystal has 28 unique protein molecules arranged in columns with sevenfold translational noncrystallographic symmetry (tNCS) along c and modulated X-ray diffraction with intensity crests at l = 7n and l = 7n ± 3. The translational NCS is combined with pseudotetragonal rotational NCS. The crystal was a perfect tetartohedral twin, although detection of twinning was severely hindered by the pseudosymmetry. The structure determined at 2.4 Å resolution reveals that the Hyp-1 molecules (packed as β-sheet dimers) have three novel ligand-binding sites (two internal and one in a surface pocket), which was confirmed by solution studies. In addition to 60 Hyp-1-docked ligands, there are 29 interstitial ANS molecules distributed in a pattern that violates the arrangement of the protein molecules and is likely to be the generator of the structural modulation. In particular, whenever the stacked Hyp-1 molecules are found closer together there is an ANS molecule bridging them.



8-anilino-1-naphthalene sulfonate, Hypericum perforatum, St John's wort, pathogenesis-related class 10 protein, Anilino Naphthalenesulfonates, Crystallography, X-Ray, Hypericum, Models, Molecular, Plant Proteins, Protein Conformation

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Acta Crystallogr D Biol Crystallogr

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International Union of Crystallography (IUCr)
Wellcome Trust (082961/Z/07/Z)
Wellcome Trust (100140/Z/12/Z)
Financial support for this project was provided by the European Union within the European Regional Developmental Fund and by the Polish Ministry of Science and Higher Education (grant No. NN 301 003739) and National Science Center (2013/10/M/NZ1/00251). RJR was supported by a Principal Research Fellowship from theWellcome Trust (grant No. 082961/Z/07/Z). ZD was supported in part by the Intramural Research Program of the National Cancer Institute, Center for Cancer Research.