title: The high-resolution crystal structure of periplasmic Haemophilus influenzae NAD nucleotidase reveals a novel enzymatic function of human CD73 related to NAD metabolism.
abstract: Haemophilus influenzae is a major pathogen of the respiratory tract in humans that has developed the capability to exploit host NAD(P) for its nicotinamide dinucleotide requirement. This strategy is organized around a periplasmic enzyme termed NadN (NAD nucleotidase), which plays a central role by degrading NAD into adenosine and NR (nicotinamide riboside), the latter being subsequently internalized by a specific permease. We performed a biochemical and structural investigation on H. influenzae NadN which determined that the enzyme is a Zn2+-dependent 5'-nucleotidase also endowed with NAD(P) pyrophosphatase activity. A 1.3 Å resolution structural analysis revealed a remarkable conformational change that occurs during catalysis between the open and closed forms of the enzyme. NadN showed a broad substrate specificity, recognizing either mono- or di-nucleotide nicotinamides and different adenosine phosphates with a maximal activity on 5'-adenosine monophosphate. Sequence and structural analysis of H. influenzae NadN led us to discover that human CD73 is capable of processing both NAD and NMN, therefore disclosing a possible novel function of human CD73 in systemic NAD metabolism. Our data may prove to be useful for inhibitor design and disclosed unanticipated fascinating evolutionary relationships.
authors.affiliation: Dipartimento di Scienze Chimiche, Alimentari, Farmaceutiche e Farmacologiche, University of Piemonte Orientale Amedeo Avogadro, Via Bovio 6, 28100 Novara, Italy. silvia.garavaglia@pharm.unipmn.it
authors.forename: Silvia
authors.initials: S
authors.lastname: Garavaglia
authors.forename: Santina
authors.initials: S
authors.lastname: Bruzzone
authors.forename: Camilla
authors.initials: C
authors.lastname: Cassani
authors.forename: Laura
authors.initials: L
authors.lastname: Canella
authors.forename: Gianna
authors.initials: G
authors.lastname: Allegrone
authors.forename: Laura
authors.initials: L
authors.lastname: Sturla
authors.forename: Elena
authors.initials: E
authors.lastname: Mannino
authors.forename: Enrico
authors.initials: E
authors.lastname: Millo
authors.forename: Antonio
authors.initials: A
authors.lastname: De Flora
authors.forename: Menico
authors.initials: M
authors.lastname: Rizzi
mesh_terms: D015720:5'-Nucleotidase / Q000378:metabolism*; D000244:Adenosine Diphosphate; D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D019556:COS Cells; D002522:Chlorocebus aethiops; D003001:Cloning, Molecular; D003460:Crystallization; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D006193:Haemophilus influenzae / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009243:NAD / Q000378:metabolism; D009537:Nicotinamide Mononucleotide / Q000378:metabolism; D009708:Nucleotidases / Q000235:genetics / Q000378:metabolism*; D011487:Protein Conformation; D011755:Pyrophosphatases / Q000235:genetics / Q000378:metabolism*; D015032:Zinc / Q000737:chemistry
chemical_list: D001426:Bacterial Proteins; D009243:NAD; D009537:Nicotinamide Mononucleotide; D000244:Adenosine Diphosphate; D009708:Nucleotidases; D015720:5'-Nucleotidase; C430338:NadN protein, Haemophilus influenzae; D011755:Pyrophosphatases; D015032:Zinc