Unraveling the Mysteries of How Methanobactin Reduces and Stabilizes Copper Ions

Abstract

Methanobactins (mb) are peptide-derived, copper-binding molecules produced by methanotrophic bacteria, which use methane as their primary source of carbon and energy. They synthesize mb to scavenge copper ions from the environment and use this copper to meet the needs of the enzyme that catalyzes the conversion of methane to methanol. The best characterized methanobactin is isolated from the bacterium Methylosinus trichosporium O3b3 (mb-O3b3). mb-O3b3 displays the remarkable property of binding and reducing copper(II) ions to copper(I) ions and stabilizing them in an aqueous environment. mb-O3b3 can also bind and reduce Mercury(II), Silver(I), and Gold(III) ions. Currently we do not know how mb-O3b3 is able to carry out these reactions. We do know from the structure of copper-bound mb-O3b3 that there are two oxazolone rings that are intimately involved in the binding of Copper(I) ions. Here we will report on a method we have developed for selectively opening these rings and isolating the products.