Requirement of the N-terminus for dimer formation of phenylalanine-sensitive 3-deoxy-D-arabino-heptulosonate synthase AroG of Escherichia coli

✍ Scribed by Jianfeng Xu; Changyun Hu; Shuiyuan Shen; Weirong Wang; Peihong Jiang; Weida Huang

• Publisher: John Wiley and Sons
• Year: 2004
• Tongue: English
• Weight: 179 KB
• Volume: 44
• Category: Article
• ISSN: 0233-111X
• DOI: 10.1002/jobm.200410396

✦ Synopsis

Abstract

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. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)