Blickling S, Renner C, Laber B, Pohlenz H D, Holak T A, Huber R
Max-Planck-Institut für Biochemie, Abteilung Strukturforschung, Martinsried, FRG.
Biochemistry. 1997 Jan 7;36(1):24-33. doi: 10.1021/bi962272d.
Dihydrodipicolinate synthase (DHDPS) catalyzes the condensation of pyruvate with L-aspartate beta-semialdehyde. It is the first enzyme unique to the diaminopimelate pathway of lysine biosynthesis. Here we present the crystal structures of five complexes of Escherichia coli DHDPS with substrates, substrate analogs, and inhibitors. These include the complexes of DHDPS with (1) pyruvate, (2) pyruvate and the L-aspartate beta-semialdehyde analog succinate beta-semialdehyde, (3) the inhibitor alpha-ketopimelic acid, (4) dipicolinic acid, and (5) the natural feedback inhibitor L-lysine. The kinetics of inhibition were determined, and the binding site of the L-lysine was identified. NMR experiments were conducted in order to elucidate the nature of the product of the reaction catalyzed by DHDPS. By this method, (4S)-4-hydroxy-2,3,4,5-tetrahydro-(2S)-dipicolinic acid is identified as the only product. A reaction mechanism for DHDPS is proposed, and important features for inhibition are identified.
二氢二吡啶二羧酸合酶（DHDPS）催化丙酮酸与L-天冬氨酸β-半醛的缩合反应。它是赖氨酸生物合成中二氨基庚二酸途径所特有的第一种酶。在此，我们展示了大肠杆菌DHDPS与底物、底物类似物和抑制剂形成的五种复合物的晶体结构。这些复合物包括DHDPS与（1）丙酮酸、（2）丙酮酸和L-天冬氨酸β-半醛类似物琥珀酸β-半醛、（3）抑制剂α-酮基庚二酸、（4）二吡啶甲酸以及（5）天然反馈抑制剂L-赖氨酸形成的复合物。测定了抑制动力学，并确定了L-赖氨酸的结合位点。进行了核磁共振实验以阐明DHDPS催化反应产物的性质。通过这种方法，鉴定出（4S）-4-羟基-2,3,4,5-四氢-（2S）-二吡啶甲酸是唯一产物。提出了DHDPS的反应机制，并确定了抑制的重要特征。
