4is4

The glutamine synthetase from the dicotyledonous plant M. truncatula is a decamer

spinqualitylabelsall models 4is4, resolution 2.35Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4is4 is a 10 chain structure with sequence from Barrel medic. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Gene: MTR_6g071070 (Barrel medic) Activity: Glutamate--ammonia ligase, with EC number 6.3.1.2 Resources: FirstGlance, OCA, RCSB, PDBsum Publication Abstract from PubMed The first step of nitrogen assimilation in higher plants, the energy-driven incorporation of ammonia into glutamate, is catalyzed by glutamine synthetase. This central process yields the readily metabolizable glutamine, which in turn is at the basis of all subsequent biosynthesis of nitrogenous compounds. The essential role performed by glutamine synthetase makes it a prime target for herbicidal compounds, but also a suitable intervention point for the improvement of crop yields. Although the majority of crop plants are dicotyledonous, little is known about the structural organization of glutamine synthetase in these organisms and about the functional differences between the different isoforms. Here, the structural characterization of two glutamine synthetase isoforms from the model legume Medicago truncatula is reported: the crystallographic structure of cytoplasmic GSII-1a and an electron cryomicroscopy reconstruction of plastid-located GSII-2a. Together, these structural models unveil a decameric organization of dicotyledonous glutamine synthetase, with two pentameric rings weakly connected by inter-ring loops. Moreover, rearrangement of these dynamic loops changes the relative orientation of the rings, suggesting a zipper-like mechanism for their assembly into a decameric enzyme. Finally, the atomic structure of M. truncatula GSII-1a provides important insights into the structural determinants of herbicide resistance in this family of enzymes, opening new avenues for the development of herbicide-resistant plants. The structures of cytosolic and plastid-located glutamine synthetases from Medicago truncatula reveal a common and dynamic architecture.,Torreira E, Seabra AR, Marriott H, Zhou M, Llorca O, Robinson CV, Carvalho HG, Fernandez-Tornero C, Pereira PJ Acta Crystallogr D Biol Crystallogr. 2014 Apr;70(Pt 4):981-93. doi:, 10.1107/S1399004713034718. Epub 2014 Mar 19. PMID:24699643 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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