4IS4

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

4IS4 の概要

• エントリーDOI: 10.2210/pdb4is4/pdb
• 分子名称: Glutamine synthetase (2 entities in total)
• 機能のキーワード: decamer dicotyledonous, ligase
• 由来する生物種: Medicago truncatula (Barrel medic)
• タンパク質・核酸の鎖数: 10
• 化学式量合計: 415504.41

構造登録者

Seabra, A.R.,Carvalho, H.,Pereira, P.J.B. (登録日: 2013-01-16, 公開日: 2014-04-09, 最終更新日: 2023-09-20)

主引用文献

Torreira, E.,Seabra, A.R.,Marriott, H.,Zhou, M.,Llorca, O.,Robinson, C.V.,Carvalho, H.G.,Fernandez-Tornero, C.,Pereira, P.J.
The structures of cytosolic and plastid-located glutamine synthetases from Medicago truncatula reveal a common and dynamic architecture.
Acta Crystallogr.,Sect.D, 70:981-993, 2014

PubMed Abstract: 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.

PubMed: 24699643
DOI: 10.1107/S1399004713034718

実験手法

X-RAY DIFFRACTION (2.35 Å)