title: Mobilization of intracellular copper stores by the ctr2 vacuolar copper transporter.
abstract: Copper plays an essential role in processes including signaling to the transcription and protein trafficking machinery, oxidative phosphorylation, iron mobilization, neuropeptide maturation, and normal development. Whereas much is known about intracellular mobilization of ions such as calcium, little information is available on how eukaryotic cells mobilize intracellular copper stores. We describe a mechanism by which the Saccharomyces cerevisiae Ctr2 protein provides bioavailable copper via mobilization of intracellular copper stores. Whereas Ctr2 exhibits structural similarity to the Ctr1 plasma membrane copper importer, microscopic and biochemical fractionation studies localize Ctr2 to the vacuole membrane. We demonstrate that Ctr2 mobilizes vacuolar copper stores in a manner dependent on amino acid residues conserved between the Ctr1 and Ctr2 copper transport family and that ctr2 Delta mutants hyper-accumulate vacuolar copper. Furthermore, a Ctr2 mutant that is mislocalized to the plasma membrane stimulates extracellular copper uptake, supporting a direct role for Ctr2 in copper transport across membranes. These studies identify a novel mechanism for copper mobilization and suggest that organisms cope with copper deprivation via the use of intracellular vesicular stores.
authors.affiliation: Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA.
authors.forename: Erin M
authors.initials: EM
authors.lastname: Rees
authors.forename: Jaekwon
authors.initials: J
authors.lastname: Lee
authors.forename: Dennis J
authors.initials: DJ
authors.lastname: Thiele
mesh_terms: D000595:Amino Acid Sequence; D027321:Anion Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D001692:Biological Transport; D027682:Cation Transport Proteins / Q000737:chemistry / Q000378:metabolism; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D017124:Conserved Sequence; D003300:Copper / Q000378:metabolism*; D000079923:Copper Transporter 1; D049452:Green Fluorescent Proteins / Q000235:genetics; D008715:Methionine; D008856:Microscopy, Fluorescence; D016296:Mutagenesis; D011993:Recombinant Fusion Proteins; D000080083:SLC31 Proteins; D012441:Saccharomyces cerevisiae / Q000737:chemistry* / Q000235:genetics / Q000648:ultrastructure; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D013329:Structure-Activity Relationship; D014617:Vacuoles / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D027321:Anion Transport Proteins; C490078:CTR1 protein, S cerevisiae; D027682:Cation Transport Proteins; D000079923:Copper Transporter 1; C497350:Ctr2 protein, S cerevisiae; D011993:Recombinant Fusion Proteins; D000080083:SLC31 Proteins; D029701:Saccharomyces cerevisiae Proteins; C485192:green fluorescent protein, Aequorea victoria; D049452:Green Fluorescent Proteins; D003300:Copper; D008715:Methionine