title: Monomeric Corynebacterium glutamicum N-acetyl glutamate kinase maintains sensitivity to L-arginine but has a lower intrinsic catalytic activity.
abstract: N-acetyl glutamate kinase (NAGK) is a key enzyme in the synthesis of L-arginine, and L-arginine-sensitive NAGK typically has hexameric architecture. Defining the relationship between this architecture and L-arginine inhibition can provide a foundation to identify the key amino acids involved in the allosteric regulation network of L-arginine. In the present study, the key amino acids in the N-terminal helix (N-helix) of Corynebacterium glutamicum (Cg) NAGK required for hexamer formation were determined using structural homology modeling and site-directed mutagenesis. It was also verified that hexameric architecture is required for the positive cooperativity of inhibition by L-arginine and for efficient catalysis, but that it is not the determinant of inhibition by L-arginine. Monomeric mutants retained a similar sensitivity to L-arginine as the hexameric form, indicating that monomers contain an independent, sensitive signal transduction network of L-arginine to mediate allosteric regulation. Mutation studies of CgNAGKs also revealed that amino acid residues 18-23 of the N-helix are required for inhibition by L-arginine, and that E19 may be an essential amino acid influencing the apparent affinity of L-arginine. Collectively, these studies may illuminate the basic mechanism of metabolic homeostasis of C. glutamicum.
authors.affiliation: Guangdong Key Laboratory of Fermentation and Enzyme Engineering, School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, 510006, People's Republic of China.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Huang
authors.affiliation: Guangdong Key Laboratory of Fermentation and Enzyme Engineering, School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, 510006, People's Republic of China.
authors.forename: Cheng
authors.initials: C
authors.lastname: Li
authors.affiliation: Guangdong Key Laboratory of Fermentation and Enzyme Engineering, School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, 510006, People's Republic of China.
authors.forename: Hao
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Guangdong Key Laboratory of Fermentation and Enzyme Engineering, School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, 510006, People's Republic of China.|Guangdong research center of Industrial enzyme and Green manufacturing technology, School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, 510006, People's Republic of China.
authors.forename: Shuli
authors.initials: S
authors.lastname: Liang
authors.affiliation: Guangdong Key Laboratory of Fermentation and Enzyme Engineering, School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, 510006, People's Republic of China.|Guangdong research center of Industrial enzyme and Green manufacturing technology, School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, 510006, People's Republic of China.
authors.forename: Shuangyan
authors.initials: S
authors.lastname: Han
authors.affiliation: Guangdong Key Laboratory of Fermentation and Enzyme Engineering, School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, 510006, People's Republic of China.|Guangdong research center of Industrial enzyme and Green manufacturing technology, School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, 510006, People's Republic of China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Lin
authors.affiliation: Guangdong Key Laboratory of Fermentation and Enzyme Engineering, School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, 510006, People's Republic of China. birxyang@scut.edu.cn.|Guangdong research center of Industrial enzyme and Green manufacturing technology, School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, 510006, People's Republic of China. birxyang@scut.edu.cn.|Key Laboratory of Renewable Energy, Chinese Academy of Sciences, Guangzhou, 510640, People's Republic of China. birxyang@scut.edu.cn.
authors.forename: Xiaorong
authors.initials: X
authors.lastname: Yang
authors.affiliation: Guangdong Key Laboratory of Fermentation and Enzyme Engineering, School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, 510006, People's Republic of China. spzheng@scut.edu.cn.|Guangdong research center of Industrial enzyme and Green manufacturing technology, School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, 510006, People's Republic of China. spzheng@scut.edu.cn.
authors.forename: Suiping
authors.initials: S
authors.lastname: Zheng
mesh_terms: D000494:Allosteric Regulation; D001120:Arginine / Q000378:metabolism*; D048230:Corynebacterium glutamicum / Q000201:enzymology*; D004252:DNA Mutational Analysis; D016297:Mutagenesis, Site-Directed; D017851:Phosphotransferases (Carboxyl Group Acceptor) / Q000235:genetics / Q000378:metabolism*; D055503:Protein Multimerization
chemical_list: D001120:Arginine; D017851:Phosphotransferases (Carboxyl Group Acceptor); C018721:acetylglutamate kinase
keywords: Hexameric architecture; Homology modeling; L-arginine inhibition; N-acetyl glutamate kinase