This Article Full Text Full Text (PDF) Supplemental Data All Versions of this Article: 20/12/3467    most recent tpc.108.063255v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Web of Science (9) Citing Articles via Google Scholar Google Scholar Articles by Charpentier, M. Articles by Parniske, M. Search for Related Content PubMed PubMed Citation Articles by Charpentier, M. Articles by Parniske, M. Agricola Articles by Charpentier, M. Articles by Parniske, M.

Lotus japonicus CASTOR and POLLUX Are Ion Channels Essential for Perinuclear Calcium Spiking in Legume Root Endosymbiosis^[W]

^a Ludwig-Maximilians-Universität München, Faculty of Biology, Genetics, 80638 München, Germany
^b Ludwig-Maximilians-Universität München, Faculty of Biology, Botany, 80638 München, Germany

¹ Address correspondence to parniske{at}lmu.de.

The mechanism underlying perinuclear calcium spiking induced during legume root endosymbioses is largely unknown. Lotus japonicus symbiosis-defective castor and pollux mutants are impaired in perinuclear calcium spiking. Homology modeling suggested that the related proteins CASTOR and POLLUX might be ion channels. Here, we show that CASTOR and POLLUX form two independent homocomplexes in planta. CASTOR reconstituted in planar lipid bilayers exhibited ion channel activity, and the channel characteristics were altered in a symbiosis-defective mutant carrying an amino acid replacement close to the selectivity filter. Permeability ratio determination and competition experiments reveled a weak preference of CASTOR for cations such as potassium over anions. POLLUX has an identical selectivity filter region and complemented a potassium transport–deficient yeast mutant, suggesting that POLLUX is also a potassium-permeable channel. Immunogold labeling localized the endogenous CASTOR protein to the nuclear envelope of Lotus root cells. Our data are consistent with a role of CASTOR and POLLUX in modulating the nuclear envelope membrane potential. They could either trigger the opening of calcium release channels or compensate the charge release during the calcium efflux as counter ion channels.

This article has been cited by other articles:

				B. J. Sieberer, M. Chabaud, A. C. Timmers, A. Monin, J. Fournier, and D. G. Barker A Nuclear-Targeted Cameleon Demonstrates Intranuclear Ca2+ Spiking in Medicago truncatula Root Hairs in Response to Rhizobial Nodulation Factors Plant Physiology, November 1, 2009; 151(3): 1197 - 1206. [Abstract] [Full Text] [PDF]

				E. Kiss, B. Olah, P. Kalo, M. Morales, A. B. Heckmann, A. Borbola, A. Lozsa, K. Kontar, P. Middleton, J. A. Downie, et al. LIN, a Novel Type of U-Box/WD40 Protein, Controls Early Infection by Rhizobia in Legumes Plant Physiology, November 1, 2009; 151(3): 1239 - 1249. [Abstract] [Full Text] [PDF]

				G. E. D. Oldroyd, M. J. Harrison, and U. Paszkowski Reprogramming Plant Cells for Endosymbiosis Science, May 8, 2009; 324(5928): 753 - 754. [Abstract] [Full Text] [PDF]