title: The Arabidopsis COPT6 transport protein functions in copper distribution under copper-deficient conditions.
abstract: Copper (Cu), an essential redox active cofactor, participates in fundamental biological processes, but it becomes highly cytotoxic when present in excess. Therefore, living organisms have established suitable mechanisms to balance cellular and systemic Cu levels. An important strategy to maintain Cu homeostasis consists of regulating uptake and mobilization via the conserved family of CTR/COPT Cu transport proteins. In the model plant Arabidopsis thaliana, COPT1 protein mediates root Cu acquisition, whereas COPT5 protein functions in Cu mobilization from intracellular storage organelles. The function of these transporters becomes critical when environmental Cu bioavailability diminishes. However, little is know about the mechanisms that mediate plant Cu distribution. In this report, we present evidence supporting an important role for COPT6 in Arabidopsis Cu distribution. Similarly to COPT1 and COPT2, COPT6 fully complements yeast mutants defective in high-affinity Cu uptake and localizes to the plasma membrane of Arabidopsis cells. Whereas COPT2 mRNA is only up-regulated upon severe Cu deficiency, COPT6 transcript is expressed under Cu excess conditions and displays a more gradual increase in response to decreases in environmental Cu levels. Consistent with COPT6 expression in aerial vascular tissues and reproductive organs, copt6 mutant plants exhibit altered Cu distribution under Cu-deficient conditions, including increased Cu in rosette leaves but reduced Cu levels in seeds. This altered Cu distribution is fully rescued when the wild-type COPT6 gene is reintroduced into the copt6 mutant line. Taken together, these findings highlight the relevance of COPT6 in shoot Cu redistribution when environmental Cu is limited.
authors.affiliation: Departament de Bioquímica i Biologia Molecular, Universitat de València, E-46100 Burjassot, Valencia, Spain.
authors.forename: Antoni
authors.initials: A
authors.lastname: Garcia-Molina
authors.forename: Nuria
authors.initials: N
authors.lastname: Andrés-Colás
authors.forename: Ana
authors.initials: A
authors.lastname: Perea-García
authors.forename: Ulla
authors.initials: U
authors.lastname: Neumann
authors.forename: Sheel C
authors.initials: SC
authors.lastname: Dodani
authors.forename: Peter
authors.initials: P
authors.lastname: Huijser
authors.forename: Lola
authors.initials: L
authors.lastname: Peñarrubia
authors.forename: Sergi
authors.initials: S
authors.lastname: Puig
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism; D003300:Copper / Q000172:deficiency / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D005816:Genetic Complementation Test; D006706:Homeostasis; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D018515:Plant Leaves / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D018520:Plant Shoots / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D058526:Plant Vascular Bundle / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D000080083:SLC31 Proteins; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D012639:Seeds / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D015854:Up-Regulation
chemical_list: D029681:Arabidopsis Proteins; C576754:COPT6 protein, Arabidopsis; D026901:Membrane Transport Proteins; D000080083:SLC31 Proteins; D003300:Copper
keywords: Arabidopsis thaliana; COPT6; Copper transport; Metal homeostasis; Nutrient deficiency