2dtj: Difference between revisions

Aspartate kinase (AK) catalyzes the first step of the biosynthesis of the aspartic acid family amino acids, and is regulated via feedback inhibition by end-products including Thr and Lys. To elucidate the mechanism of this inhibition, we determined the crystal structure of the regulatory subunit of AK from Corynebacterium glutamicum at 1.58 A resolution in the Thr-binding form, the first crystal structure of the regulatory subunit of alpha(2)beta(2)-type AK. The regulatory subunit contains two ACT domain motifs per monomer and is arranged as a dimer. Two non-equivalent ACT domains from different chains form an effector-binding unit that binds a single Thr molecule, and the resulting two effector-binding units of the dimer associate perpendicularly in a face-to-face manner. The regulatory subunit is a monomer in the absence of Thr but becomes a dimer by adding Thr. The dimerization is eliminated in mutant AKs with changes in the Thr-binding region, suggesting that the dimerization induced by Thr binding is a key step in the inhibitory mechanism of AK from C. glutamicum. A putative Lys-binding site and the inhibitory mechanism of CgAK are discussed.

Structural Insight into concerted inhibition of alpha 2 beta 2-type aspartate kinase from Corynebacterium glutamicum., Yoshida A, Tomita T, Kurihara T, Fushinobu S, Kuzuyama T, Nishiyama M, J Mol Biol. 2007 Apr 27;368(2):521-36. Epub 2007 Feb 20. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=17350037 17350037]

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