3c20 | pdb_00003c20

Crystal Structure of Threonine-sensitive Aspartokinase from Methanococcus jannaschii with L-aspartate

spinqualitylabelsall models 3c20, resolution 2.70Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3c20 is a 2 chain structure with sequence from Methanocaldococcus jannaschii. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.7Å Ligands: ASP, FMT Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function AK_METJA Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed The commitment step to the aspartate pathway of amino acid biosynthesis is the phosphorylation of aspartic acid catalyzed by aspartokinase (AK). Most microorganisms and plants have multiple forms of this enzyme, and many of these isofunctional enzymes are subject to feedback regulation by the end products of the pathway. However, the archeal species Methanococcus jannaschii has only a single, monofunctional form of AK. The substrate l-aspartate binds to this recombinant enzyme in two different orientations, providing the first structural evidence supporting the relaxed regiospecificity previously observed with several alternative substrates of Escherichia coli AK ( Angeles, T. S., Hunsley, J. R., and Viola, R. E. (1992) Biochemistry 31, 799-805 ). Binding of the nucleotide substrate triggers significant domain movements that result in a more compact quaternary structure. In contrast, the highly cooperative binding of the allosteric regulator l-threonine to multiple sites on this dimer of dimers leads to an open enzyme structure. A comparison of these structures supports a mechanism for allosteric regulation in which the domain movements induced by threonine binding causes displacement of the substrates from the enzyme, resulting in a relaxed, inactive conformation. The structural basis for allosteric inhibition of a threonine-sensitive aspartokinase.,Liu X, Pavlovsky AG, Viola RE J Biol Chem. 2008 Jun 6;283(23):16216-25. Epub 2008 Mar 11. PMID:18334478 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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