title: Histidine 416 of the periplasmic binding protein NikA is essential for nickel uptake in Escherichia coli.
abstract: Escherichia coli require nickel for the synthesis of [NiFe] hydrogenases under anaerobic growth conditions. Nickel import depends on the specific ABC-transporter NikABCDE encoded by the nik operon, which deletion causes the complete abolition of hydrogenase activity. We have previously postulated that the periplasmic binding protein NikA binds a natural metallophore containing three carboxylate functions that coordinate a Ni(II) ion, the fourth ligand being His416, the only direct metal-protein contact, completing a square-planar coordination for the metal. The crystal structure of the H416I mutant showed no electron density corresponding to a metal-chelator complex. In vivo experiments indicate that the mutation causes a significant decrease in nickel uptake and hydrogenase activity. These results confirm the essential role of His416 in nickel transport by NikA.
authors.affiliation: Institut de Biologie Structurale Jean-Pierre Ebel, UMR 5075, CEA, CNRS, Université Joseph Fourier-Grenoble 1, Grenoble, France. christine.cavazza@ibs.fr
authors.forename: Christine
authors.initials: C
authors.lastname: Cavazza
authors.forename: Lydie
authors.initials: L
authors.lastname: Martin
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Laffly
authors.forename: Hugo
authors.initials: H
authors.lastname: Lebrette
authors.forename: Mickaël V
authors.initials: MV
authors.lastname: Cherrier
authors.forename: Laura
authors.initials: L
authors.lastname: Zeppieri
authors.forename: Pierre
authors.initials: P
authors.lastname: Richaud
authors.forename: Marie
authors.initials: M
authors.lastname: Carrière
authors.forename: Juan C
authors.initials: JC
authors.lastname: Fontecilla-Camps
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D019943:Amino Acid Substitution; D001692:Biological Transport; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000737:chemistry / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006639:Histidine / Q000737:chemistry / Q000378:metabolism*; D006864:Hydrogenase / Q000378:metabolism; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D050505:Mutant Proteins / Q000737:chemistry / Q000378:metabolism; D009532:Nickel / Q000032:analysis / Q000378:metabolism*; D033902:Periplasmic Binding Proteins / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation
chemical_list: D018528:ATP-Binding Cassette Transporters; D029968:Escherichia coli Proteins; D050505:Mutant Proteins; D033902:Periplasmic Binding Proteins; C089849:nikA protein, E coli; D006639:Histidine; D009532:Nickel; C043296:nickel-iron hydrogenase; D006864:Hydrogenase