title: Molecular and biochemical properties of two P1B2-ATPases, CsHMA3 and CsHMA4, from cucumber.
abstract: P1B-ATPases (heavy metal ATPases, HMAs) constitute a multigenic subfamily of P-ATPases involved in the transport of monovalent and divalent heavy metals in plant cells. Here, we present the organization of genes encoding the HMA family in the cucumber genome and report the function and biochemical properties of two cucumber proteins homologous to the HMA2-4-like plant HMAs. Eight genes encoding putative P1B -ATPases were identified in the cucumber genome. Among them, CsHMA3 was predominantly expressed in roots and up-regulated by Pb, Zn and Cd excess, whereas the CsHMA4 transcript was most abundant in roots and flowers of cucumber plants, and elevated under Pb and Zn excess. Expression of CsHMA3 in Saccharomyces cerevisiae enhanced yeast tolerance to Cd and Pb, whereas CsHMA4 conferred increased resistance of yeast cells to Cd and Zn. Immunostaining with specific antibodies raised against cucumber proteins revealed tonoplast localization of CsHMA3 and plasma membrane localization of CsHMA4 in cucumber root cells. Kinetic studies of CsHMA3 and CsHMA4 in yeast membranes indicated differing heavy metal cation affinities of these two proteins. Altogether, the results suggest an important role of CsHMA3 and CsHMA4 in Cd and Pb detoxification and Zn homeostasis in cucumber cells.
authors.affiliation: Department of Plant Molecular Physiology, Institute of Experimental Biology, University of Wroclaw Kanonia 6/8, Wroclaw, 50-328, Poland.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Migocka
authors.forename: Anna
authors.initials: A
authors.lastname: Papierniak
authors.forename: Ewa
authors.initials: E
authors.lastname: Maciaszczyk-Dziubinska
authors.forename: Ewelina
authors.initials: E
authors.lastname: Posyniak
authors.forename: Anna
authors.initials: A
authors.lastname: Kosieradzka
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D002104:Cadmium / Q000378:metabolism; D002462:Cell Membrane / Q000201:enzymology; D018553:Cucumis sativus / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D035264:Flowers / Q000201:enzymology; D017343:Genes, Plant / Q000235:genetics; D006706:Homeostasis; D007854:Lead / Q000378:metabolism; D019216:Metals, Heavy / Q000378:metabolism*; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000201:enzymology; D030821:Plants, Genetically Modified / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D015032:Zinc / Q000378:metabolism
chemical_list: D019216:Metals, Heavy; D010940:Plant Proteins; D002104:Cadmium; D007854:Lead; D000251:Adenosine Triphosphatases; D015032:Zinc
keywords: detoxification; genome; heavy metals; heavy metal ATPases; plasma membrane; tonoplast