title: Crystal structure of nicotinic acid mononucleotide adenylyltransferase from Pseudomonas aeruginosa in its Apo and substrate-complexed forms reveals a fully open conformation.
abstract: The enzyme nicotinic acid mononucleotide adenylyltransferase (NaMN AT; EC 2.7.7.18) is essential for the synthesis of nicotinamide adenine dinucleotide and is a potential target for antibiotics. It catalyzes the transfer of an AMP moiety from ATP to nicotinic acid mononucleotide to form nicotinic acid adenine dinucleotide. In order to provide missing structural information on the substrate complexes of NaMN AT and to assist structure-based design of specific inhibitors for antibacterial discovery, we have determined the crystal structure of NaMN AT from Pseudomonas aeruginosa in three distinct states, i.e. the NaMN-bound form at 1.7A resolution and ATP-bound form at 2.0A as well as its apo-form at 2.0A. They represent crucial structural information necessary for better understanding of the substrate recognition and the catalytic mechanism. The substrate-unbound and substrate-complexed structures are all in the fully open conformation and there is little conformational change upon binding each of the substrates. Our structures indicate that a conformational change is necessary to bring the two substrates closer together for initiating the catalysis. We suggest that such a conformational change likely occurs only after both substrates are simultaneously bound in the active site.
authors: Department of Chemistry, College of Natural Sciences, Seoul National University, Seoul 151-742, South Korea.
authors: Hye-Jin
authors: HJ
authors: Yoon
authors: Hye Lee
authors: HL
authors: Kim
authors: Bunzo
authors: B
authors: Mikami
authors: Se Won
authors: SW
authors: Suh
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D002384:Catalysis; D018360:Crystallography, X-Ray; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009612:Nicotinamide-Nucleotide Adenylyltransferase / Q000737:chemistry*; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011550:Pseudomonas aeruginosa / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D013237:Stereoisomerism; D013379:Substrate Specificity
chemical_list: D009612:Nicotinamide-Nucleotide Adenylyltransferase; C038480:nicotinic acid mononucleotide adenylyltransferase