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Domain motions of glucosamine‐6P synthase: Comparison of the anisotropic displacements in the crystals and the catalytic hinge‐bending rotation
Author(s) -
Mouilleron Stéphane,
GolinelliPimpaneau Béatrice
Publication year - 2007
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1110/ps.062598107
Subject(s) - glutamine amidotransferase , glutaminase , atp synthase , chemistry , crystallography , hinge , rotation (mathematics) , rigid body , glutamine , enzyme , physics , geometry , biochemistry , classical mechanics , mathematics , amino acid
Glucosamine‐6‐phosphate synthase channels ammonia over 18 Å from glutamine at the glutaminase site to fructose‐6P at the synthase site. We have modeled the anisotropic displacements of the glutaminase and synthase domains from the two crystallized states, the enzyme in complex with fructose‐6P or in complex with glucose‐6P and a glutamine affinity analog, using TLS (rigid‐body motion in terms of translation, libration, and screw motions) refinement implemented in REFMAC . The domains displacements in the crystal lattices are compared to the movement of the glutaminase domain relative to the synthase domain that occurs during the catalytic cycle upon glutamine binding, which was visualized by comparing the two structures. This movement was analyzed by the program DYNDOM as a 22.8° rotation around an effective hinge axis running approximately parallel to helix 300–317 of the synthase domain, the glutaminase loop that covers the glutaminase site upon glutamine binding acting as the mechanical hinge.