Anno2014
AutoriBoccaccio, Anna; Scholz-Starke, Joachim; Hamamoto, Shin; Larisch, Nina; Festa, Margherita; Gutla, Paul Vijay Kanth; Costa, Alex; Dietrich, Petra; Uozumi, Nobuyuki; Carpaneto, Armando
AbstractTwo-pore channel proteins (TPC) encode intracellular ion channels in both animals and plants. In mammalian cells, the two isoforms (TPC1 and TPC2) localize to the endo-lysosomal compartment, whereas the plant TPC1 protein is targeted to the membrane surrounding the large lytic vacuole. Although it is well established that plant TPC1 channels activate in a voltage- and calcium-dependent manner in vitro, there is still debate on their activation under physiological conditions. Likewise, the mode of animal TPC activation is heavily disputed between two camps favoring as activator either nicotinic acid adenine dinucleotide phosphate (NAADP) or the phosphoinositide PI(3,5)P-2. Here, we investigated TPC current responses to either of these second messengers by whole-vacuole patch-clamp experiments on isolated vacuoles of Arabidopsis thaliana. After expression in mesophyll protoplasts from Arabidopsis tpc1 knock-out plants, we detected the Arabidopsis TPC1-EGFP and human TPC2-EGFP fusion proteins at the membrane of the large central vacuole. Bath (cytosolic) application of either NAADP or PI(3,5)P-2 did not affect the voltage- and calcium-dependent characteristics of AtTPC1-EGFP. By contrast, PI(3,5)P-2 elicited large sodium currents in hTPC2-EGFP-containing vacuoles, while NAADP had no such effect. Analogous results were obtained when PI(3,5)P-2 was applied to hTPC2 expressed in baker's yeast giant vacuoles. Our results underscore the fundamental differences in the mode of current activation and ion selectivity between animal and plant TPC proteins and corroborate the PI(3,5)P-2-mediated activation and Na+ selectivity of mammalian TPC2.
RivistaCellular And Molecular Life Sciences (print. Ed.)
ISSN1420-682X
Impact factor0
Volume71
Pagina inizio4275
Pagina fine4283
Autori IBFArmando CARPANETO, Anna Elisabetta BOCCACCIO, Paul Vijay Kanth GUTLA, Joachim Johannes SCHOLZ STARKE, Margherita FESTA
Linee di Ricerca IBFMD.P01.001.001
Sedi IBFIBF.GE