This protein family includes the periplasmic copper-binding protein CueP from Salmonella enterica and similar bacterial sequences. CueP is related to copper-resistance, copper-storage and is as an essential factor in the transfer of copper ions, playing a role in the suppression of oxidative stress. CueP, which adopts a dimeric assembly, consists of two domains: an N-terminal domain with two alpha-helices and three beta-strands organized into a beta-sheet and a larger C-terminal domain that comprises a four-stranded beta-sheet and a two-stranded beta-sheet that face each other [1-3].

1: Structure of the periplasmic copper-binding protein CueP from Salmonella enterica serovar Typhimurium. Yoon BY, Kim YH, Kim N, Yun BY, Kim JS, Lee JH, Cho HS, Lee K, Ha NC; Acta Crystallogr D Biol Crystallogr. 2013;69:1867-1875. PMID:24100307

2: Alternative periplasmic copper-resistance mechanisms in Gram negative bacteria. Pontel LB, Soncini FC; Mol Microbiol. 2009;73:212-225. PMID:19538445

3: Copper homeostasis in Salmonella is atypical and copper-CueP is a major periplasmic metal complex. Osman D, Waldron KJ, Denton H, Taylor CM, Grant AJ, Mastroeni P, Robinson NJ, Cavet JS; J Biol Chem. 2010;285:25259-25268. PMID:20534583