Conformational changes in ammonia-channeling glutamine amidotransferases.
Glutamine amidotransferases (GATs), which catalyze the synthesis of different aminated products, channel ammonia over 10-40 A from a glutamine substrate at the glutaminase site to an acceptor substrate at the synthase site. Ammonia production usually uses a cysteine-histidine-glutamate triad or a N-terminal cysteine residue. Crystal structures of several amidotransferase ligand complexes, mimicking intermediates along the catalytic cycle, have now been determined. In most cases, acceptor binding triggers glutaminase activation through domain-hinged movements and other conformational changes. Structural information shows how flexible loops of the synthase and glutaminase domains move to shield the two catalytic sites and anchor the substrates, and how the ammonia channel forms and opens or closes.
Mouilleron
Stéphane
S
Laboratoire d'Enzymologie et Biochimie structurales, CNRS Bâtiment 34, 1 avenue de la Terrasse, 91190 Gif-sur-Yvette, France.
Golinelli-Pimpaneau
Béatrice
B
D000641:Ammonia / Q000378:metabolism*; D000878:Anthranilate Synthase / Q000737:chemistry / Q000378:metabolism*; D002384:Catalysis; D020134:Catalytic Domain; D008958:Models, Molecular; D019884:Nitrogenous Group Transferases / Q000737:chemistry / Q000378:metabolism*; D011487:Protein Conformation
D000641:Ammonia; D019884:Nitrogenous Group Transferases; D000878:Anthranilate Synthase; C020655:anthranilate synthase, glutamine amidotransferase subunit