title: Brassica juncea plant cadmium resistance 1 protein (BjPCR1) facilitates the radial transport of calcium in the root.
abstract: Calcium (Ca) is an important structural component of plant cell walls and an intracellular messenger in plants and animals. Therefore, plants tightly control the balance of Ca by regulating Ca uptake and its transfer from cell to cell and organ to organ. Here, we propose that Brassica juncea PCR1 (PCR1), a member of the plant cadmium resistance (PCR) protein family in Indian mustard, is a Ca(2+) efflux transporter that is required for the efficient radial transfer of Ca(2+) in the root and is implicated in the translocation of Ca to the shoot. Knock-down lines of BjPCR1 were greatly stunted and translocated less Ca to the shoot than did the corresponding WT. The localization of BjPCR1 to the plasma membrane and the preferential expression of BjPCR1 in the root epidermal cells of WT plants suggest that BjPCR1 antisense plants could not efficiently transfer Ca(2+) from the root epidermis to the cells located inside the root. Protoplasts isolated from BjPCR1 antisense lines had lower Ca(2+) efflux activity than did those of the WT, and membrane vesicles isolated from BjPCR1-expressing yeast exhibited increased Ca(2+) transport activity. Inhibitor studies, together with theoretical considerations, indicate that BjPCR1 exports one Ca(2+) in exchange for three protons. Root hair-specific expression of BjPCR1 in Arabidopsis results in plants that exhibit increased Ca(2+) resistance and translocation. In conclusion, our data support the hypothesis that BjPCR1 is an exporter required for the translocation of Ca(2+) from the root epidermis to the inner cells, and ultimately to the shoot.
authors.affiliation: Institute of Plant Biology,  University of Zurich, CH-8008 Zurich,  Switzerland.
authors.forename: Won-Yong
authors.initials: WY
authors.lastname: Song
authors.forename: Kwan-Sam
authors.initials: KS
authors.lastname: Choi
authors.forename: De Angeli
authors.initials: de A
authors.lastname: Alexis
authors.forename: Enrico
authors.initials: E
authors.lastname: Martinoia
authors.forename: Youngsook
authors.initials: Y
authors.lastname: Lee
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism*; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D017403:In Situ Hybridization; D017136:Ion Transport; D008969:Molecular Sequence Data; D009149:Mustard Plant / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D019441:Plant Epidermis / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D011523:Protoplasts / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid
chemical_list: D027682:Cation Transport Proteins; D010940:Plant Proteins; D020033:Protein Isoforms; D002118:Calcium
references.citation: Biochim Biophys Acta. 2002 Aug 31;1564(2):299-309
references.pmid: 12175911
references.citation: J Biol Chem. 1990 Jun 15;265(17):9617-20
references.pmid: 2351660
references.citation: Plant Cell. 2004 May;16(5):1327-39
references.pmid: 15100400
references.citation: J Exp Bot. 2001 May;52(358):891-9
references.pmid: 11432906
references.citation: Biophys J. 2002 Apr;82(4):1943-52
references.pmid: 11916852
references.citation: Plant Cell. 2002 Dec;14(12):3237-53
references.pmid: 12468740
references.citation: Plant Physiol. 2004 Dec;136(4):4318-25
references.pmid: 15531711
references.citation: Plant Cell. 2010 Mar;22(3):541-63
references.pmid: 20354197
references.citation: J Biol Chem. 1980 Jan 10;255(1):39-44
references.pmid: 6985610
references.citation: Ann Bot. 2003 Oct;92(4):487-511
references.pmid: 12933363
references.citation: J Membr Biol. 1990 Mar;114(2):133-42
references.pmid: 2160540
references.citation: Plant Physiol. 2004 Jun;135(2):1027-39
references.pmid: 15181212
references.citation: J Exp Bot. 2001 May;52(358):1051-61
references.pmid: 11432921
references.citation: Plant Physiol. 2004 Apr;134(4):1793-802
references.pmid: 15064381
references.citation: Mol Cells. 2011 Jan;31(1):1-7
references.pmid: 21347707
references.citation: Science. 2000 Jul 7;289(5476):85-8
references.pmid: 10884229
references.citation: Plant Cell. 2010 Apr;22(4):1057-73
references.pmid: 20400678
references.citation: Plant Cell. 2010 Jul;22(7):2237-52
references.pmid: 20647347
references.citation: EMBO Rep. 2007 Mar;8(3):228-32
references.pmid: 17290287
references.citation: Curr Opin Plant Biol. 2009 Jun;12(3):250-8
references.pmid: 19473870
references.citation: J Physiol. 2000 Dec 15;529 Pt 3:611-23
references.pmid: 11195933