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| [[Image:2c2b.gif|left|200px]] | | {{Seed}} |
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| {{STRUCTURE_2c2b| PDB=2c2b | SCENE= }} | | {{STRUCTURE_2c2b| PDB=2c2b | SCENE= }} |
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| '''CRYSTALLOGRAPHIC STRUCTURE OF ARABIDOPSIS THALIANA THREONINE SYNTHASE COMPLEXED WITH PYRIDOXAL PHOSPHATE AND S-ADENOSYLMETHIONINE'''
| | ===CRYSTALLOGRAPHIC STRUCTURE OF ARABIDOPSIS THALIANA THREONINE SYNTHASE COMPLEXED WITH PYRIDOXAL PHOSPHATE AND S-ADENOSYLMETHIONINE=== |
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| ==Overview==
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| Threonine synthase (TS) is a fold-type II pyridoxal phosphate (PLP)-dependent enzyme that catalyzes the ultimate step of threonine synthesis in plants and microorganisms. Unlike the enzyme from microorganisms, plant TS is activated by S-adenosylmethionine (AdoMet). The mechanism of activation has remained unknown up to now. We report here the crystallographic structures of Arabidopsis thaliana TS in complex with PLP (aTS) and with PLP and AdoMet (aTS-AdoMet), which show with atomic detail how AdoMet activates TS. The aTS structure reveals a PLP orientation never previously observed for a type II PLP-dependent enzyme and explains the low activity of plant TS in the absence of its allosteric activator. The aTS-AdoMet structure shows that activation of the enzyme upon AdoMet binding triggers a large reorganization of active site loops in one monomer of the structural dimer and allows the displacement of PLP to its active conformation. Comparison with other TS structures shows that activation of the second monomer may be triggered by substrate binding. This structure also discloses a novel fold for two AdoMet binding sites located at the dimer interface, each site containing two AdoMet effectors bound in tandem. Moreover, aTS-AdoMet is the first structure of an enzyme that uses AdoMet as an allosteric effector.
| | The line below this paragraph, {{ABSTRACT_PUBMED_16319072}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 16319072 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_16319072}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Synthase]] | | [[Category: Synthase]] |
| [[Category: Threonine synthesis]] | | [[Category: Threonine synthesis]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 21:08:31 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 12:11:26 2008'' |
