2020

Acta Crystallographica Section D-Structural Biology

Rocznik: 2020 | Tom: 76 | Numer: 7

artykuł naukowy

angielski

EN Superstructure modulation, with violation of the strict short-range periodic order of consecutive crystal unit cells, is well known in small-molecule crystallography but is rarely reported for macromolecular crystals. To date, one modulated macromolecular crystal structure has been successfully determined and refined for a pathogenesis-related class 10 protein fromHypericum perforatum(Hyp-1) crystallized as a complex with 8-anilinonaphthalene-1-sulfonate (ANS) [Sliwiaket al.(2015),Acta Cryst.D71, 829-843]. The commensurate modulation in that case was interpreted in a supercell with sevenfold expansion alongc. When crystallized in the additional presence of melatonin, the Hyp-1-ANS complex formed crystals with a different pattern of structure modulation, in which the supercell shows a ninefold expansion ofc, manifested in the diffraction pattern by a wave of reflection-intensity modulation with crests atl= 9nandl= 9n +/- 4. Despite complicated tetartohedral twinning, the structure has been successfully determined and refined to 2.3 angstrom resolution using a description in a ninefold-expanded supercell, with 36 independent Hyp-1 chains and 156 ANS ligands populating the three internal (95 ligands) and five interstitial (61 ligands) binding sites. The commensurate superstructures and ligand-binding sites of the two crystal structures are compared, with a discussion of the effect of melatonin on the co-crystallization process.

653 - 667

10.1107/S2059798320006841

http://journals.iucr.org/d/issues/2020/07/00/mf5041/mf5041.pdf

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07.2020

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