Heavy metal transport by AtHMA4 involves the N-terminal degenerated metal binding domain and the C-terminal His11 stretch.
The Arabidopsis thaliana AtHMA4 is a P1B-type ATPase that clusters with the Zn/Cd/Pb/Co subgroup. It has been previously shown, by heterologous expression and the study of AtHMA4 knockout or overexpressing lines in Arabidopsis , that AtHMA4 is implicated in zinc homeostasis and cadmium tolerance. Here, we report the study of the heterologous expression of AtHMA4 in the yeast Saccharomyces cerevisiae. AtHMA4 expression resulted in an increased tolerance to Zn, Cd and Pb and to a phenotypic complementation of hypersensitive mutants. In contrast, an increased sensitivity towards Co was observed. An AtHMA4::GFP fusion protein was observed in endocytic vesicles and at the yeast plasma membrane. Mutagenesis of the cysteine and glutamate residues from the N-ter degenerated heavy metal binding domain impaired the function of AtHMA4. It was also the case when the C-ter His11 stretch was deleted, giving evidence that these amino acids are essential for the AtHMA4 binding/translocation of metals.
Verret
Frédéric
F
CEA Cadarache, DSV/DEVM/Laboratoire des Echanges Membranaires et Signalisation, UMR 6191 CNRS-CEA-Aix-Marseille II - F-13108 St. Paul les Durance Cedex, France.
Gravot
Antoine
A
Auroy
Pascaline
P
Preveral
Sandra
S
Forestier
Cyrille
C
Vavasseur
Alain
A
Richaud
Pierre
P
D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000737:chemistry / Q000235:genetics; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D001692:Biological Transport; D002104:Cadmium / Q000378:metabolism / Q000494:pharmacology; D015870:Gene Expression; D006639:Histidine / Q000235:genetics / Q000378:metabolism*; D007854:Lead / Q000378:metabolism / Q000494:pharmacology; D019216:Metals, Heavy / Q000378:metabolism* / Q000494:pharmacology; D008861:Microsomes / Q000378:metabolism; D016297:Mutagenesis, Site-Directed / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D015032:Zinc / Q000378:metabolism / Q000494:pharmacology
D029681:Arabidopsis Proteins; D019216:Metals, Heavy; D002104:Cadmium; D007854:Lead; D006639:Histidine; D000251:Adenosine Triphosphatases; C477864:HMA4 protein, Arabidopsis; D015032:Zinc