Title
Impact of copper ligand mutations on a cupredoxin with a green copper center
Author
Magali Roger, Giuliano Sciara, Frédéric Biaso, Elisabeth Lojou, Xie Wang, Marielle Bauzan, Marie-Thérèse Giudici-Orticoni, Alejandro Vila, Marianne Ilbert
Year
2017
Journal
Biochimica et Biophysica Acta (BBA) - Bioenergetics
Abstract
Mononuclear cupredoxins contain a type 1 copper center with a trigonal or tetragonal geometry usually maintained by four ligands, a cystein, two histidines and a methionine. The recent discovery of new members of this family with unusual properties demonstrates, however, the versatility of this class of proteins. Changes in their ligand set lead to drastic variation in their metal site geometry and in the resulting spectroscopic and redox features. In our work, we report the identification of the copper ligands in the recently discovered cupredoxin AcoP. We show that eventhough AcoP possesses a classical copper ligand set, it has a highly perturbed copper center. In depth studies of mutant's properties suggest a high degree of constraint existing in the copper center of the wild type protein and even the addition of exogenous ligands does not lead to the reconstitution of the initial copper center. Not only the chemical nature of the axial ligand but also constraints brought by its covalent binding to the protein backbone might be critical to maintain a green copper site with high redox potential. This work illustrates the importance of experimentally dissecting the molecular diversity of cupredoxins to determine the molecular determinants responsible for their copper center geometry and redox potential.
Instrument
J-715
Keywords
Circular dichroism, Secondary structure, Ligand binding, Coordination chemistry, Biochemistry