biostudies-literatureWaldron KJBiotechnology and Biological Sciences Research Council32504-11https://www.ebi.ac.uk/biostudies/studies/S-EPMC2952252biostudies-literatureUnknown285(42)A copper-trafficking pathway was found to enable Cu(2+) occupancy of a soluble periplasm protein, CucA, even when competing Zn(2+) is abundant in the periplasm. Here, we solved the structure of CucA (a new cupin) and found that binding of Cu(2+), but not Zn(2+), quenches the fluorescence of Trp(165), which is adjacent to the metal site. Using this fluorescence probe, we established that CucA becomes partly occupied by Zn(2+) following exposure to equimolar Zn(2+) and Cu(2+). Cu(2+)-CucA is more thermodynamically stable than Zn(2+)-CucA but k((Zn→Cu)exchange) is slow, raising questions about how the periplasm contains solely the Cu(2+) form. We discovered that a copper-trafficking pathway involving two copper transporters (CtaA and PacS) and a metallochaperone (Atx1) is obligatory for Cu(2+The Journal of biological chemistryStructure and metal loading of a soluble periplasm cuproprotein.PMC2952252BB/E001688/1BBS/B/02576Robinson NJWaldron KJFirbank SJTottey SPerez-Rama MDainty SJfalseStructure and metal loading of a soluble periplasm cuproprotein.A copper-trafficking pathway was found to enable Cu(2+) occupancy of a soluble periplasm protein, CucA, even when competing Zn(2+) is abundant in the periplasm. Here, we solved the structure of CucA (a new cupin) and found that binding of Cu(2+), but not Zn(2+), quenches the fluorescence of Trp(165), which is adjacent to the metal site. Using this fluorescence probe, we established that CucA becomes partly occupied by Zn(2+) following exposure to equimolar Zn(2+) and Cu(2+). Cu(2+)-CucA is more thermodynamically stable than Zn(2+)-CucA but k((Zn→Cu)exchange) is slow, raising questions about how the periplasm contains solely the Cu(2+) form. We discovered that a copper-trafficking pathway involving two copper transporters (CtaA and PacS) and a metallochaperone (Atx1) is obligatory for Cu(2+2010-01-01T00:00:00Z2010 Oct2026-04-29T18:51:56.653Z2019-03-27T00:34:45ZS-EPMC29522522070241110.1074/jbc.M110.15308010.1074/jbc.m110.153080