Poster: Membrane Transport

Abs # 1234: Evaluating the role of cyclic nucleotides in modulation of native plant cell inward Ca and K currents

Presenter:	Lemtiri-Chlieh, Fouad , flemtiri@canr.uconn.edu
Authors	Lemtiri-Chlieh, Fouad  (A)   Berkowitz, Gerald A (A)
Affiliations:	(A): University of Connecticut, Plant Science Department

Cyclic nucleotides (cNMPs) have been shown to increase in response to various compounds such as kinetin, atrial natriuretic peptide (ANP) and plant natriuretic peptide immunoanalogues (irPNP) that promote stomatal opening. The effect of cGMP on stomatal opening appears to be linked with Ca levels (Pharmawati et al., Plant physiol Biochem 39:385). Cyclic nucleotides have also been shown to modulate K and Na currents across the plasma membrane of plant cells (Li et al., PNAS 90:262, Maathuis & Sanders, Plant Physiol. 127:1617). Previous work from this lab involving expression and voltage clamp analysis of Arabidopsis cyclic nucleotides gated channels (CNGCs) has clearly demonstrated K and Ca permeability upon addition of cNMPs, (Leng et al., Plant Physiol 121:753 & 128:400). The objective of the work reported here is to investigate the possible role CNGCs play in inward Ca and K currents across native plant cell membranes. Modulation by cNMPs of native plant cell ion channels could occur directly, as is the case with CNGCs, or indirectly. Members of other channel families can be indirectly modulated by cNMP through the intermediary action of cNMP-dependent kinases. Protoplasts were isolated from various tissues of Arabidopsis plants. Whole-cell voltage clamp recordings were made from protoplasts in the presence and absence of lipophilic cyclic nucleotide analogs (dibutyryl-, and 8-bromo-cNMP) added to the recording bath. We are dissecting the molecular basis for cNMP involvement in regulation of native plant channels by comparing effect of cNMP application in the whole-cell, verses patch configuration. Supported by NSF award 0090675.