A combined zinc/cadmium sensor and zinc/cadmium export regulator in a heavy metal pump
Baekgaard, Lone, Mikkelsen, Maria D., Sorensen, Danny M., Hegelund, Josefine N., Persson, Daniel P., Mills, Rebecca F., Yang, Zhang, Husted, Søren, Andersen, Jens Peter, Buch-Pedersen, Morten J., Schjoerring, Jan K., Williams, Lorraine E. and Palmgren, Michael G. (2010) A combined zinc/cadmium sensor and zinc/cadmium export regulator in a heavy metal pump. Journal of Biological Chemistry, 285, (41), 31243-31252. (doi:10.1074/jbc.M110.111260). (PMID:20650903).
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Heavy metal pumps (P1B-ATPases) are important for cellular heavy metal homeostasis. AtHMA4, an Arabidopsis thaliana heavy metal pump of importance for plant Zn2+ nutrition, has an extended C-terminal domain containing 13 cysteine pairs and a terminal stretch of 11 histidines. Using a novel size-exclusion chromatography, inductively coupled plasma mass spectrometry approach we report that the C-terminal domain of AtHMA4 is a high affinity Zn2+ and Cd2+ chelator with capacity to bind 10 Zn2+ ions per C terminus. When AtHMA4 is expressed in a Zn2+-sensitive zrc1 cot1 yeast strain, sequential removal of the histidine stretch and the cysteine pairs confers a gradual increase in Zn2+ and Cd2+ tolerance and lowered Zn2+ and Cd2+ content of transformed yeast cells. We conclude that the C-terminal domain of AtHMA4 serves a dual role as Zn2+ and Cd2+ chelator (sensor) and as a regulator of the efficiency of Zn2+ and Cd2+ export. The identification of a post-translational handle on Zn2+ and Cd2+ transport efficiency opens new perspectives for regulation of Zn2+ nutrition and tolerance in eukaryotes.
|Keywords:||atpases, plant, plasma membrane, transport metals, zinc, cadmium, p-type pump, regulatory domain|
|Subjects:||Q Science > QH Natural history > QH301 Biology
Q Science > QH Natural history > QH426 Genetics
R Medicine > R Medicine (General)
|Divisions:||University Structure - Pre August 2011 > School of Biological Sciences
|Date Deposited:||12 May 2011 10:43|
|Last Modified:||01 Jun 2011 15:41|
|RDF:||RDF+N-Triples, RDF+N3, RDF+XML, Browse.|
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