2d3b
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Crystal Structure of the Maize Glutamine Synthetase complexed with AMPPNP and Methionine sulfoximine
OverviewOverview
Plants provide nourishment for animals and other heterotrophs as the sole primary producer in the food chain. Glutamine synthetase (GS), one of the essential enzymes for plant autotrophy catalyzes the incorporation of ammonia into glutamate to generate glutamine with concomitant hydrolysis of ATP, and plays a crucial role in the assimilation and re-assimilation of ammonia derived from a wide variety of metabolic processes during plant growth and development. Elucidation of the atomic structure of higher plant GS is important to understand its detailed reaction mechanism and to obtain further insight into plant productivity and agronomical utility. Here we report the first crystal structures of maize (Zea mays L.) GS. The structure reveals a unique decameric structure that differs significantly from the bacterial GS structure. Higher plants have several isoenzymes of GS differing in heat stability and catalytic properties for efficient responses to variation in the environment and nutrition. A key residue responsible for the heat stability was found to be Ile-161 in GS1a. The three structures in complex with substrate analogues, including phosphinothricin, a widely used herbicide, lead us to propose a mechanism for the transfer of phosphate from ATP to glutamate and to interpret the inhibitory action of phosphinothricin as a guide for the development of new potential herbicides.
About this StructureAbout this Structure
2D3B is a Single protein structure of sequence from Zea mays with , and as ligands. Active as Glutamate--ammonia ligase, with EC number 6.3.1.2 Full crystallographic information is available from OCA.
ReferenceReference
Atomic structure of plant glutamine synthetase: a key enzyme for plant productivity., Unno H, Uchida T, Sugawara H, Kurisu G, Sugiyama T, Yamaya T, Sakakibara H, Hase T, Kusunoki M, J Biol Chem. 2006 Sep 29;281(39):29287-96. Epub 2006 Jul 7. PMID:16829528
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