title: Two metal-tolerance proteins, MTP1 and MTP4, are involved in Zn homeostasis and Cd sequestration in cucumber cells.
abstract: Metal-tolerance proteins (MTPs) are divalent cation transporters that have been shown to be essential for metal homeostasis and tolerance in model plants and hyperaccumulators. Due to the lack of genomic resources, studies on MTPs in cultivated crops are lacking. Here, we present the first functional characterization of genes encoding cucumber proteins homologous to MTP1 and MTP4 transporters. CsMTP1 expression was ubiquitous in cucumber plants, whereas CsMTP4 mRNA was less abundant and was not detected in the generative parts of the flowers. When expressed in yeast, CsMTP1 and CsMTP4 were able to complement the hypersensitivity of mutant strains to Zn and Cd through the increased sequestration of metals within vacuoles using the transmembrane electrochemical gradient. Both proteins formed oligomers at the vacuolar membranes of yeast and cucumber cells and localized in Arabidopsis protoplasts, consistent with their function in vacuolar Zn and Cd sequestration. Changes in the abundance of CsMTP1 and CsMTP4 transcripts and proteins in response to elevated Zn and Cd, or to Zn deprivation, suggested metal-induced transcriptional, translational, and post-translational modifications of protein activities. The differences in the organ expression and affinity of both proteins to Zn and Cd suggested that CsMTP1 and CsMTP4 may not be functionally redundant in cucumber cells.
authors.affiliation: Department of Molecular Plant Physiology, Wroclaw University, Institute of Experimental Biology, Kanonia 6/8, 50-328 Wroclaw, Poland mmigocka@biol.uni.wroc.pl.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Migocka
authors.affiliation: Department of Molecular Plant Physiology, Wroclaw University, Institute of Experimental Biology, Kanonia 6/8, 50-328 Wroclaw, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Kosieradzka
authors.affiliation: Department of Molecular Plant Physiology, Wroclaw University, Institute of Experimental Biology, Kanonia 6/8, 50-328 Wroclaw, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Papierniak
authors.affiliation: Department of Genetics and Cell Physiology, Wroclaw University, Institute of Experimental Biology, Kanonia 6/8, 50-328 Wroclaw, Poland.
authors.forename: Ewa
authors.initials: E
authors.lastname: Maciaszczyk-Dziubinska
authors.affiliation: Department of Molecular Plant Physiology, Wroclaw University, Institute of Experimental Biology, Kanonia 6/8, 50-328 Wroclaw, Poland.
authors.forename: Ewelina
authors.initials: E
authors.lastname: Posyniak
authors.affiliation: Department of Animal Developmental Biology, Wroclaw University, Institute of Experimental Biology, Sienkiewicza 21, 50-335 Wroclaw, Poland.
authors.forename: Arnold
authors.initials: A
authors.lastname: Garbiec
authors.affiliation: Institut des Sciences du Végétal, Centre National de la Recherche Scientifique (CNRS), 1 Avenue de la Terrasse, Saclay Plant Sciences Labex, 91198 Gif-Sur-Yvette Cedex, France Université Paris 7-Denis Diderot, UFR Sciences du Vivant, 35 rue Hélène Brion, 75205 Paris Cedex 13, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Filleur
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002104:Cadmium / Q000378:metabolism*; D027682:Cation Transport Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D018553:Cucumis sativus / Q000235:genetics* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D006706:Homeostasis / Q000187:drug effects; D008969:Molecular Sequence Data; D030781:Organisms, Genetically Modified / Q000235:genetics / Q000378:metabolism; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D012989:Soil Pollutants / Q000378:metabolism*; D014617:Vacuoles / Q000378:metabolism; D015032:Zinc / Q000378:metabolism*
chemical_list: D027682:Cation Transport Proteins; D010940:Plant Proteins; D012989:Soil Pollutants; D002104:Cadmium; D015032:Zinc
keywords: Cucumber; heavy metals; membrane proteins; metal-tolerance proteins; vacuole.