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Molecular symmetry‐constrained systematic search approach to structure solution of the coiled‐coil SRGAP2 F‐BARx domain
Author(s) -
Sporny Michael,
Guez-Haddad Julia,
Waterman David G.,
Isupov Michail N.,
Opatowsky Yarden
Publication year - 2016
Publication title -
acta crystallographica section d
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.374
H-Index - 138
ISSN - 2059-7983
DOI - 10.1107/s2059798316016697
Subject(s) - coiled coil , crystallography , bar (unit) , domain (mathematical analysis) , monoclinic crystal system , symmetry (geometry) , resolution (logic) , physics , protein filament , diffraction , chemistry , biophysics , crystal structure , geometry , biology , optics , computer science , mathematics , mathematical analysis , biochemistry , artificial intelligence , meteorology
SRGAP2 (Slit–Robo GTPase‐activating protein 2) is a cytoplasmic protein found to be involved in neuronal branching, restriction of neuronal migration and restriction of the length and density of dendritic postsynaptic spines. The extended F‐BAR (F‐BARx) domain of SRGAP2 generates membrane protrusions when expressed in COS‐7 cells, while most F‐BARs induce the opposite effect: membrane invaginations. As a first step to understand this discrepancy, the F‐BARx domain of SRGAP2 was isolated and crystallized after co‐expression with the carboxy domains of the protein. Diffraction data were collected from two significantly non‐isomorphous crystals in the same monoclinic C 2 space group. A correct molecular‐replacment solution was obtained by applying a molecular symmetry‐constrained systematic search approach that took advantage of the conserved biological symmetry of the F‐BAR domains. It is shown that similar approaches can solve other F‐BAR structures that were previously determined by experimental phasing. Diffraction data were reprocessed with a high‐resolution cutoff of 2.2 Å, chosen using less strict statistical criteria. This has improved the outcome of multi‐crystal averaging and other density‐modification procedures.