title: Copper-regulated trafficking of the Menkes disease copper ATPase is associated with formation of a phosphorylated catalytic intermediate.
abstract: The Menkes protein (MNK; ATP7A) is a copper-transporting P-type ATPase that is defective in the copper deficiency disorder, Menkes disease. MNK is localized in the trans-Golgi network and transports copper to enzymes synthesized within secretory compartments. However, in cells exposed to excessive copper, MNK traffics to the plasma membrane where it functions in copper efflux. A conserved feature of all P-type ATPases is the formation of an acyl-phosphate intermediate, which occurs as part of the catalytic cycle during cation transport. In this study we investigated the effect of mutations within conserved catalytic regions of MNK on intracellular localization and trafficking from the trans-Golgi network (TGN). Our findings suggest that mutations that block formation of the phosphorylated catalytic intermediate also prevent copper-induced relocalization of MNK from the TGN. Furthermore, mutations in the phosphatase domain, which resulted in hyperphosphorylation of MNK, caused constitutive trafficking from the TGN to the plasma membrane. A similar effect on trafficking was observed with a phosphatase mutation in the closely related copper ATPase, ATP7B, affected in Wilson disease. These findings suggest that the copper-induced trafficking of the Menkes and Wilson disease copper ATPases is associated with the phosphorylated intermediate that is formed during the catalysis of these pumps. Our findings describe a novel mechanism for regulating the subcellular location of a transport protein involving the recognition of intermediate conformations during catalysis.
authors.affiliation: Department of Nutritional Sciences, University of Missouri, Columbia, Missouri 65211, USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Petris
authors.forename: Ilia
authors.initials: I
authors.lastname: Voskoboinik
authors.forename: Michael
authors.initials: M
authors.lastname: Cater
authors.forename: Kathryn
authors.initials: K
authors.lastname: Smith
authors.forename: Byung-Eun
authors.initials: BE
authors.lastname: Kim
authors.forename: Roxana M
authors.initials: RM
authors.lastname: Llanos
authors.forename: Daniel
authors.initials: D
authors.lastname: Strausak
authors.forename: James
authors.initials: J
authors.lastname: Camakaris
authors.forename: Julian F B
authors.initials: JF
authors.lastname: Mercer
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D015153:Blotting, Western; D016466:CHO Cells; D002384:Catalysis; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism*; D003300:Copper / Q000502:physiology*; D000073840:Copper-Transporting ATPases; D006224:Cricetinae; D005455:Fluorescent Antibody Technique; D005816:Genetic Complementation Test; D016296:Mutagenesis; D010766:Phosphorylation; D021381:Protein Transport; D011993:Recombinant Fusion Proteins; D013347:Subcellular Fractions / Q000201:enzymology
chemical_list: D027682:Cation Transport Proteins; D011993:Recombinant Fusion Proteins; D003300:Copper; D000251:Adenosine Triphosphatases; C081184:ATP7A protein, human; D000073840:Copper-Transporting ATPases