Mechanism of concerted inhibition of alpha2beta2-type hetero-oligomeric aspartate kinase from Corynebacterium glutamicum.
Aspartate kinase (AK) is the first and committed enzyme of the biosynthetic pathway producing aspartate family amino acids, lysine, threonine, and methionine. AK from Corynebacterium glutamicum (CgAK), a bacterium used for industrial fermentation of amino acids, including glutamate and lysine, is inhibited by lysine and threonine in a concerted manner. To elucidate the mechanism of this unique regulation in CgAK, we determined the crystal structures in several forms: an inhibitory form complexed with both lysine and threonine, an active form complexed with only threonine, and a feedback inhibition-resistant mutant (S301F) complexed with both lysine and threonine. CgAK has a characteristic alpha(2)beta(2)-type heterotetrameric structure made up of two alpha subunits and two beta subunits. Comparison of the crystal structures between inhibitory and active forms revealed that binding inhibitors causes a conformational change to a closed inhibitory form, and the interaction between the catalytic domain in the alpha subunit and beta subunit (regulatory subunit) is a key event for stabilizing the inhibitory form. This study shows not only the first crystal structures of alpha(2)beta(2)-type AK but also the mechanism of concerted inhibition in CgAK.
Yoshida
Ayako
A
Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
Tomita
Takeo
T
Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
Kuzuyama
Tomohisa
T
Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
Nishiyama
Makoto
M
Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan. Electronic address: umanis@mail.ecc.u-tokyo.ac.jp.
D000596:Amino Acids / Q000737:chemistry* / Q000378:metabolism; D001222:Aspartate Kinase / Q000737:chemistry* / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D020134:Catalytic Domain; D048230:Corynebacterium glutamicum / Q000201:enzymology*; D018360:Crystallography, X-Ray; D020836:Protein Structure, Quaternary; D013329:Structure-Activity Relationship
D000596:Amino Acids; D001426:Bacterial Proteins; D001222:Aspartate Kinase