title: Spectral and thermodynamic properties of Ag(I), Au(III), Cd(II), Co(II), Fe(III), Hg(II), Mn(II), Ni(II), Pb(II), U(IV), and Zn(II) binding by methanobactin from Methylosinus trichosporium OB3b.
abstract: Methanobactin (mb) is a novel chromopeptide that appears to function as the extracellular component of a copper acquisition system in methanotrophic bacteria. To examine this potential physiological role, and to distinguish it from iron binding siderophores, the spectral (UV-visible absorption, circular dichroism, fluorescence, and X-ray photoelectron) and thermodynamic properties of metal binding by mb were examined. In the absence of Cu(II) or Cu(I), mb will bind Ag(I), Au(III), Co(II), Cd(II), Fe(III), Hg(II), Mn(II), Ni(II), Pb(II), U(VI), or Zn(II), but not Ba(II), Ca(II), La(II), Mg(II), and Sr(II). The results suggest metals such as Ag(I), Au(III), Hg(II), Pb(II) and possibly U(VI) are bound by a mechanism similar to Cu, whereas the coordination of Co(II), Cd(II), Fe(III), Mn(II), Ni(II) and Zn(II) by mb differs from Cu(II). Consistent with its role as a copper-binding compound or chalkophore, the binding constants of all the metals examined were less than those observed with Cu(II) and copper displaced other metals except Ag(I) and Au(III) bound to mb. However, the binding of different metals by mb suggests that methanotrophic activity also may play a role in either the solubilization or immobilization of many metals in situ.
authors.affiliation: Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA 50011-3211, USA. dwon@iastate.edu
authors.forename: Dong W
authors.initials: DW
authors.lastname: Choi
authors.forename: Young S
authors.initials: YS
authors.lastname: Do
authors.forename: Corbin J
authors.initials: CJ
authors.lastname: Zea
authors.forename: Marcus T
authors.initials: MT
authors.lastname: McEllistrem
authors.forename: Sung-W
authors.initials: SW
authors.lastname: Lee
authors.forename: Jeremy D
authors.initials: JD
authors.lastname: Semrau
authors.forename: Nicola L
authors.initials: NL
authors.lastname: Pohl
authors.forename: Clint J
authors.initials: CJ
authors.lastname: Kisting
authors.forename: Lori L
authors.initials: LL
authors.lastname: Scardino
authors.forename: Scott C
authors.initials: SC
authors.lastname: Hartsel
authors.forename: Eric S
authors.initials: ES
authors.lastname: Boyd
authors.forename: Gill G
authors.initials: GG
authors.lastname: Geesey
authors.forename: Theran P
authors.initials: TP
authors.lastname: Riedel
authors.forename: Peter H
authors.initials: PH
authors.lastname: Shafe
authors.forename: Kim A
authors.initials: KA
authors.lastname: Kranski
authors.forename: John R
authors.initials: JR
authors.lastname: Tritsch
authors.forename: William E
authors.initials: WE
authors.lastname: Antholine
authors.forename: Alan A
authors.initials: AA
authors.lastname: DiSpirito
mesh_terms: D002942:Circular Dichroism; D007093:Imidazoles / Q000378:metabolism*; D008670:Metals / Q000378:metabolism*; D020581:Methylosinus; D046529:Microscopy, Electron, Transmission; D009842:Oligopeptides / Q000378:metabolism*; D011485:Protein Binding; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D013816:Thermodynamics
chemical_list: D007093:Imidazoles; D008670:Metals; D009842:Oligopeptides; C491147:methanobactin