NOVEL EMBRACE OF PROTEIN AND METAL

Abstract

A COPPER-TRAFFICKING PROTEIN has been found to have a unique type of metal-binding mechanism that may ease copper release. A team led by chemistry professor Thomas V. O’Halloran of Northwestern University reports that the bacterial copper-trafficking protein CusF binds copper via a strong cation-ð interaction between Cu(I) and a key tryptophan ( Nat. Chem. Bio. , DOI: 10.1038/ nchembio. 2007.57). Proteins usually bind metals through covalent interactions. CusF binds Cu(I) in a three-coordinate structure with two methionines and a histidine. Copper also interacts with the indole ring of a nearby tryptophan that stacks on top of it. The team used resonance Raman and Xray spectroscopy to confirm that the Cu-tryptophan interaction is an electrostatic cation-ð type. The Ag(I)- bound form of the binding site’s structure, though not this interaction, was independently reported last year by a team led by biologist Megan M. McEvoy of the University of Arizona ( Protein Sci. 2007 , 16 , 2287). When the researchers ...