CusF is a periplasmic protein involved in copper and silver resistance in Escherichia coil. CusF forms a five-stranded beta-barrel OB fold. Cu(I) binds to H36, M47 and M49 which are conserved residues in the protein [1].

1: A novel copper-binding fold for the periplasmic copper resistance protein CusF. Loftin IR, Franke S, Roberts SA, Weichsel A, Heroux A, Montfort WR, Rensing C, McEvoy MM; Biochemistry. 2005;44:10533-10540. PMID:16060662