title: Structure of the complex of Neisseria gonorrhoeae N-acetyl-L-glutamate synthase with a bound bisubstrate analog.
abstract: N-Acetyl-L-glutamate synthase catalyzes the conversion of AcCoA and glutamate to CoA and N-acetyl-L-glutamate (NAG), the first step of the arginine biosynthetic pathway in lower organisms. In mammals, NAG is an obligate cofactor of carbamoyl phosphate synthetase I in the urea cycle. We have previously reported the structures of NAGS from Neisseria gonorrhoeae (ngNAGS) with various substrates bound. Here we reported the preparation of the bisubstrate analog, CoA-S-acetyl-L-glutamate, the crystal structure of ngNAGS with CoA-NAG bound, and kinetic studies of several active site mutants. The results are consistent with a one-step nucleophilic addition-elimination mechanism with Glu353 as the catalytic base and Ser392 as the catalytic acid. The structure of the ngNAGS-bisubstrate complex together with the previous ngNAGS structures delineates the catalytic reaction path for ngNAGS.
authors.affiliation: Center for Genetic Medicine Research and Department of Integrative Systems Biology, Children's National Medical Center, The George Washington University, Washington, DC 20010, USA.
authors.forename: Gengxiang
authors.initials: G
authors.lastname: Zhao
authors.forename: Norma M
authors.initials: NM
authors.lastname: Allewell
authors.forename: Mendel
authors.initials: M
authors.lastname: Tuchman
authors.forename: Dashuang
authors.initials: D
authors.lastname: Shi
mesh_terms: D000214:Acyl Coenzyme A / Q000737:chemistry*; D051046:Amino-Acid N-Acetyltransferase / Q000737:chemistry* / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D002384:Catalysis; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D005971:Glutamates / Q000737:chemistry*; D009344:Neisseria gonorrhoeae / Q000201:enzymology*; D017433:Protein Structure, Secondary; D013379:Substrate Specificity
chemical_list: D000214:Acyl Coenzyme A; D001426:Bacterial Proteins; D005971:Glutamates; D051046:Amino-Acid N-Acetyltransferase