Structural Insight into concerted inhibition of alpha 2 beta 2-type aspartate kinase from Corynebacterium glutamicum.
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.
Yoshida
Ayako
A
Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
Tomita
Takeo
T
Kurihara
Takeshi
T
Fushinobu
Shinya
S
Kuzuyama
Tomohisa
T
Nishiyama
Makoto
M
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
D008024:Ligands; D050505:Mutant Proteins; D011994:Recombinant Proteins; C000204:S-2-aminoethyl cysteine; D013912:Threonine; D001222:Aspartate Kinase; D008239:Lysine; D003545:Cysteine