Poster: Membrane Transport

Abs # 1226: Functional analysis of a novel rice calcium channel

Presenter:	Hashimoto, Kenji , 3425217301@jcom.home.ne.jp
Authors	Hashimoto, Kenji  (A)   Saito, Mikako  (A)   Matsuoka, Hideaki  (A)   Iida, Kazuko  (B)   Iida, Hidetoshi  (C)
Affiliations:	(A): Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology (B): The Tokyo Metropolitan Institute of Medical Science (C): Tokyo Gakugei University

We have found that elicitor and electric stimulus (30 V / 5 mm, 30 sec) induce the transient calcium influx, which increase chitinase mRNA levels in cultured rice cells (Oryza sativa L. japonica cv. Nipponbare). Some calcium channel blockers inhibited the increase of intracellular calcium concentration and chitinase gene expression. Therefore, we focused on calcium channels as the key to understanding the electrical regulation of gene expression in cultured rice cells. However, except for an Arabidopsis thaliana voltage-gated calcium channel (AtTPC1), there is no molecular biological finding of calcium channel in plant cells. In this study we aimed at cloning and functional analysis of rice calcium channel gene. Using RT-PCR derived from AtTPC1 sequence, a full-length cDNA (2823 bp) was isolated as a candidate for a novel rice calcium channel. The cDNA clone had a 2274 bp insert containing a single open reading frame of 758 amino acids and showed about 70 % homology to AtTPC1 protein. Furthermore, the hydropathy profile showed significant structural features of the a-subunit of animal L-type voltage-gated calcium channel. Accordingly, we named this gene OsCC1 (Oryza sativa calcium channel 1). For the functional analysis of OsCC1 protein, we expressed OsCC1 in Saccharomyces cerevisiae mutant cells that were deficient in a voltage-gated calcium channel (CCH1), and measured the calcium uptake. Then OsCC1 protein rescued the calcium uptake activity of the mutant. These results suggested that OsCC1 is a novel calcium channel gene of rice.