title: Structural Insight into concerted inhibition of alpha 2 beta 2-type aspartate kinase from Corynebacterium glutamicum.
abstract: 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.
authors.affiliation: Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Ayako
authors.initials: A
authors.lastname: Yoshida
authors.forename: Takeo
authors.initials: T
authors.lastname: Tomita
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kurihara
authors.forename: Shinya
authors.initials: S
authors.lastname: Fushinobu
authors.forename: Tomohisa
authors.initials: T
authors.lastname: Kuzuyama
authors.forename: Makoto
authors.initials: M
authors.lastname: Nishiyama
mesh_terms: D000595:Amino Acid Sequence; D001222:Aspartate Kinase / Q000037:antagonists & inhibitors* / Q000737:chemistry*; D001665:Binding Sites; D048230:Corynebacterium glutamicum / Q000187:drug effects / Q000201:enzymology*; D018360:Crystallography, X-Ray; D003545:Cysteine / Q000031:analogs & derivatives / Q000494:pharmacology; D019281:Dimerization; D004352:Drug Resistance, Microbial; D025461:Feedback, Physiological / Q000187:drug effects; D008024:Ligands; D008239:Lysine / Q000378:metabolism; D008969:Molecular Sequence Data; D008970:Molecular Weight; D050505:Mutant Proteins / Q000737:chemistry; D009154:Mutation / Q000235:genetics; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000378:metabolism; D013329:Structure-Activity Relationship; D013912:Threonine / Q000378:metabolism
chemical_list: D008024:Ligands; D050505:Mutant Proteins; D011994:Recombinant Proteins; C000204:S-2-aminoethyl cysteine; D013912:Threonine; D001222:Aspartate Kinase; D008239:Lysine; D003545:Cysteine