title: Force-induced chemical reactions on the metal centre in a single metalloprotein molecule.
abstract: Metalloproteins play indispensable roles in biology owing to the versatile chemical reactivity of metal centres. However, studying their reactivity in many metalloproteins is challenging, as protein three-dimensional structure encloses labile metal centres, thus limiting their access to reactants and impeding direct measurements. Here we demonstrate the use of single-molecule atomic force microscopy to induce partial unfolding to expose metal centres in metalloproteins to aqueous solution, thus allowing for studying their chemical reactivity in aqueous solution for the first time. As a proof-of-principle, we demonstrate two chemical reactions for the FeS4 centre in rubredoxin: electrophilic protonation and nucleophilic ligand substitution. Our results show that protonation and ligand substitution result in mechanical destabilization of the FeS4 centre. Quantum chemical calculations corroborated experimental results and revealed detailed reaction mechanisms. We anticipate that this novel approach will provide insights into chemical reactivity of metal centres in metalloproteins under biologically more relevant conditions.
authors.affiliation: Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z1.|School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210063, P. R. China.
authors.forename: Peng
authors.initials: P
authors.lastname: Zheng
authors.affiliation: Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Avenue Lineu Prestes 748, São Paulo SP 05508-900, Brazil.
authors.forename: Guilherme M
authors.initials: GM
authors.lastname: Arantes
authors.affiliation: Institut de Biologie Structurale (IBS) Jean-Pierre Ebel, CEA/CNRS/Universite Joseph Fourier, 71 Avenue des Martyrs, CS 10090, Grenoble 9 38044, France.
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Field
authors.affiliation: Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z1.
authors.forename: Hongbin
authors.initials: H
authors.lastname: Li
mesh_terms: D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D008024:Ligands; D008667:Metalloproteins / Q000737:chemistry*; D018625:Microscopy, Atomic Force / Q000379:methods*; D015202:Protein Engineering; D012416:Rubredoxins / Q000737:chemistry* / Q000378:metabolism
chemical_list: D008024:Ligands; D008667:Metalloproteins; D012416:Rubredoxins