title: The binding mode of ATP revealed by the solution structure of the N-domain of human ATP7A.
abstract: We report the solution NMR structures of the N-domain of the Menkes protein (ATP7A) in the ATP-free and ATP-bound forms. The structures consist of a twisted antiparallel six-stranded beta-sheet flanked by two pairs of alpha-helices. A protein loop of 50 amino acids located between beta 3 and beta 4 is disordered and mobile on the subnanosecond time scale. ATP binds with an affinity constant of (1.2 +/- 0.1) x 10(4) m(-1) and exchanges with a rate of the order of 1 x 10(3) s(-1). The ATP-binding cavity is considerably affected by the presence of the ligand, resulting in a more compact conformation in the ATP-bound than in the ATP-free form. This structural variation is due to the movement of the alpha1-alpha2 and beta2-beta 3 loops, both of which are highly conserved in copper(I)-transporting P(IB)-type ATPases. The present structure reveals a characteristic binding mode of ATP within the protein scaffold of the copper(I)-transporting P(IB)-type ATPases with respect to the other P-type ATPases. In particular, the binding cavity contains mainly hydrophobic aliphatic residues, which are involved in van der Waal's interactions with the adenine ring of ATP, and a Glu side chain, which forms a crucial hydrogen bond to the amino group of ATP.
authors.affiliation: Magnetic Resonance Center (CERM) and Department of Chemistry, University of Florence, Italy.
authors.forename: Lucia
authors.initials: L
authors.lastname: Banci
authors.forename: Ivano
authors.initials: I
authors.lastname: Bertini
authors.forename: Francesca
authors.initials: F
authors.lastname: Cantini
authors.forename: Sayaka
authors.initials: S
authors.lastname: Inagaki
authors.forename: Manuele
authors.initials: M
authors.lastname: Migliardi
authors.forename: Antonio
authors.initials: A
authors.lastname: Rosato
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D001665:Binding Sites; D002151:Calorimetry; D027682:Cation Transport Proteins / Q000737:chemistry* / Q000378:metabolism*; D003300:Copper / Q000737:chemistry / Q000378:metabolism; D000073840:Copper-Transporting ATPases; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary
chemical_list: D001426:Bacterial Proteins; D027682:Cation Transport Proteins; C071263:CopA protein, Bacteria; D003300:Copper; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; C081184:ATP7A protein, human; D000073840:Copper-Transporting ATPases