Please use this identifier to cite or link to this item:
|Title:||A redox switch in CopC: An intriguing copper trafficking protein that binds copper(I) and copper(II) at different sites||Authors:||F., Arnesano
A. R., Thompsett
|Keywords:||XAS; copper transport; CopC; redox switch||Issue Date:||2003||Project:||None||Journal:||PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA||Abstract:||
The protein CopC from Pseudomonas syringae has been found capable of binding copper(I) and copper(II) at two different sites, occupied either one at a time or simultaneously. The protein, consisting of 102 amino acids, is known to bind copper(II) in a position that is now found consistent with a coordination arrangement including His-1, Glu-27, Asp-89, and His-91. A full solution structure analysis is reported here for Cu(I)-CopC. The copper(I) site is constituted by His-48 and three of the four Met residues (40, 43, 46, 51), which are clustered in a Met-rich region. Both copper binding sites have been characterized through extended x-ray absorption fine structure studies. They represent novel coordination environments for copper in proteins. The two sites are approximate to30 Angstrom far apart and have little affinity for the ion in the other oxidation state. Oxidation of Cu(I)-CopC or reduction of Cu(II)-CopC causes migration of copper from one site to the other. This behavior is observed both in NMR and EXAFS studies and indicates that CopC can exchange copper between two sites activated by a redox switch. CopC resides in the periplasm of Gram-negative bacteria where there is a multicopper oxidase, CopA, which may modulate the redox state of copper. CopC and CopA are coded in the same operon, responsible for copper resistance. These peculiar and novel properties of CopC are discussed with respect to their relevance for copper homeostasis.
|Appears in Collections:||Publications|
Show full item record
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.