Open AccessLikelihood‐based molecular‐replacement solution for a highly pathological crystal with tetartohedral twinning and sevenfold translational noncrystallographic symmetry
Author(s) -
Sliwiak Joanna,
Jaskolski Mariusz,
Dauter Zbigniew,
McCoy Airlie J.,
Read Randy J.
Publication year - 2014
Publication title -
acta crystallographica section d
Language(s) - English
Resource type - Journals
ISSN - 1399-0047
DOI - 10.1107/s1399004713030319
Subject(s) - crystal twinning , molecular replacement , crystallography , phaser , symmetry (geometry) , group (periodic table) , monomer , crystal structure , chemistry , molecule , resolution (logic) , physics , computer science , mathematics , geometry , optics , microstructure , artificial intelligence , organic chemistry , polymer
Translational noncrystallographic symmetry (tNCS) is a pathology of protein crystals in which multiple copies of a molecule or assembly are found in similar orientations. Structure solution is problematic because this breaks the assumptions used in current likelihood‐based methods. To cope with such cases, new likelihood approaches have been developed and implemented in Phaser to account for the statistical effects of tNCS in molecular replacement. Using these new approaches, it was possible to solve the crystal structure of a protein exhibiting an extreme form of this pathology with seven tetrameric assemblies arrayed along the c axis. To resolve space‐group ambiguities caused by tetartohedral twinning, the structure was initially solved by placing 56 copies of the monomer in space group P 1 and using the symmetry of the solution to define the true space group, C 2. The resulting structure of Hyp‐1, a pathogenesis‐related class 10 (PR‐10) protein from the medicinal herb St John's wort, reveals the binding modes of the fluorescent probe 8‐anilino‐1‐naphthalene sulfonate (ANS), providing insight into the function of the protein in binding or storing hydrophobic ligands.