Requirement of the N-terminus for dimer formation of phenylalanine-sensitive 3-deoxy-D-arabino-heptulosonate synthase AroG of Escherichia coli.
The first regulatory step in the synthesis of aromatic amino acids is catalyzed by 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase (DAHPS). In Escherichia coli, the allosteric DAHPS exists as three isozymes, AroG, AroF and AroH, each independently feedback-inhibited by corresponding end product amino acids, phenylalanine, tyrosine and typtophan. Structural biological evidences have suggested that the N-terminus of AroG is involved in the formation of a putative inhibitor-binding site and feedback inhibition signal transmission. Our previous work showed that a single amino acid residue replacement Ile10Ala or deletion of 15 N-terminal amino acids could lead to a dramatic loss of AroG enzymatic activity (Hu et al. 2003). Here we demonstrate that the deletion of N-terminus prevents the enzyme from forming a dimeric structure, indicating that the N-terminus of AroG plays a critical role in the formation of the essential tight dimeric structure.
Xu
Jianfeng
J
Department of Biochemistry, School of Life Sciences, Fudan University, Shanghai 200433, China.
Hu
Changyun
C
Shen
Shuiyuan
S
Wang
Weirong
W
Jiang
Peihong
P
Huang
Weida
W
D010723:3-Deoxy-7-Phosphoheptulonate Synthase; D000446:Aldehyde-Lyases / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D019943:Amino Acid Substitution; D001665:Binding Sites; D019281:Dimerization; D004926:Escherichia coli / Q000201:enzymology*; D025461:Feedback, Physiological; D008958:Models, Molecular; D010649:Phenylalanine / Q000378:metabolism; D017384:Sequence Deletion / Q000235:genetics / Q000502:physiology
D010649:Phenylalanine; D010723:3-Deoxy-7-Phosphoheptulonate Synthase; D000446:Aldehyde-Lyases