title: The Schizosaccharomyces pombe Pccs protein functions in both copper trafficking and metal detoxification pathways.
abstract: Because copper is both an essential cofactor and a toxic metal, different strategies have evolved to appropriately regulate its homeostasis as a function of changing environmental copper levels. In this report, we describe a metallochaperone-like protein from Schizosaccharomyces pombe that maintains the delicate balance between essentiality and toxicity. This protein, designated Pccs, has four distinct domains. SOD activity assays reveal that the first three domains of Pccs are necessary and sufficient to deliver copper to its target, copper-zinc superoxide dismutase (SOD1). Pccs domain IV, which is absent in Saccharomyces cerevisiae CCS1, contains seventeen cysteine residues, eight pairs of which are in a potential metal coordination arrangement, Cys-Cys. We show that S. cerevisiae ace1Delta mutant cells expressing the full-length Pccs molecule are resistant to copper toxicity. Furthermore, we demonstrate that the Pccs domain IV enhances copper resistance of the ace1Delta cells by an order of magnitude compared with that observed in the same strain expressing a pccs+ I-II-III allele encoding Pccs domains I-III. We consistently found that S. pombe cells disrupted in the pccs+ gene exhibit an increased sensitivity to copper and cadmium. Furthermore, we demonstrate that overexpression of pccs+ is associated with increased copper resistance in fission yeast cells. Taken together, our findings suggest that Pccs activates apo-SOD1 under copper-limiting conditions through the use of its first three domains and protects cells against metal ion toxicity via its fourth domain.
authors.affiliation: Département de Biochimie, Université de Sherbrooke, 3001 12e Avenue Nord, Sherbrooke, Québec J1H 5N4, Canada.
authors.forename: Julie
authors.initials: J
authors.lastname: Laliberté
authors.forename: Lisa J
authors.initials: LJ
authors.lastname: Whitson
authors.forename: Jude
authors.initials: J
authors.lastname: Beaudoin
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Holloway
authors.forename: P John
authors.initials: PJ
authors.lastname: Hart
authors.forename: Simon
authors.initials: S
authors.lastname: Labbé
mesh_terms: D000483:Alleles; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001692:Biological Transport; D002104:Cadmium / Q000737:chemistry; D003300:Copper / Q000737:chemistry / Q000378:metabolism*; D003545:Cysteine / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D049452:Green Fluorescent Proteins; D006801:Humans; D007477:Ions; D008164:Luminescent Proteins / Q000378:metabolism; D018832:Molecular Chaperones / Q000737:chemistry / Q000502:physiology*; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D012568:Schizosaccharomyces / Q000378:metabolism*; D029702:Schizosaccharomyces pombe Proteins / Q000737:chemistry / Q000502:physiology*; D017386:Sequence Homology, Amino Acid; D012834:Silver / Q000737:chemistry; D013482:Superoxide Dismutase / Q000737:chemistry; D000072105:Superoxide Dismutase-1; D013696:Temperature; D013997:Time Factors; D015032:Zinc / Q000737:chemistry
chemical_list: D007477:Ions; D008164:Luminescent Proteins; D018832:Molecular Chaperones; C488259:Pccs protein, S pombe; D012333:RNA, Messenger; C000606290:SOD1 protein, human; D029702:Schizosaccharomyces pombe Proteins; D002104:Cadmium; D049452:Green Fluorescent Proteins; D012834:Silver; D003300:Copper; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1; D015032:Zinc; D003545:Cysteine