《植物生理学报》 2011, 47(2): 191-198

甜瓜钾离子通道MIRK受Na+抑制的分子机理

王黎敏¹, Anne-Aliénor Véry², 张屹东¹, 邓扬悟¹, 黄丹枫^1,*

1上海交通大学农业与生物学院, 植物科学研究所, 上海200240; 2法国国家农业部植物生物化学与分子生理学中心, 法国蒙彼利埃34060

通信作者：黄丹枫；E-mail: hdf@sjtu.edu.cn；Tel: 021-34206943

摘　要：

甜瓜钾离子通道MIRK受Na+抑制, 本研究通过钾离子通道氨基酸序列比对, 发现MIRK与其他钾离子通道在3个位点 上有较明显差异。采用基因定点突变方法获得3个MIRK突变体, 将突变体在非洲爪蟾卵母(Xenopus laevis oocytes)细胞中 表达后利用双向电压钳技术研究了Na+对MIRK通道电流的调整作用, 以探索MIRK受Na+抑制的可能氨基酸位点。结果显 示, MIRK受外界Na+的抑制不是由其单一氨基酸引起, 可能涉及MIRK第232~234位丝氨酸、赖氨酸、谷氨酰胺及第241位 天冬酰胺等多个氨基酸的共同调节。

关键词：甜瓜钾离子通道MIRK; 突变体; 外界Na+; 抑制; 电生理

收稿：2010-11-24   修定：2010-12-24

资助：上海市科委基础研究重点项目(09JC1408500)、上海市蔬菜学重点学科(B209)、高等学校博士点专项科研基金 (20090073110047)和“Arcus 2006 Languedoc-Roussillon/ China”项目。

Molecular Mechanism of Melon Potassium Channel MIRK Inhibited by Na⁺

WANG Li-Min¹, Anne-Aliénor Véry², ZHANG Yi-Dong¹, DENG Yang-Wu¹, HUANG Dan-Feng^1,*

¹Institute of Plant Science, School of Agriculture and Biology, Shanghai Jiaotong University, Shanghai 200240, China; ²Biochemistry and Plant Molecular Physiology, French National Institute for Agricultural Research, Montpellier 34060, France

Corresponding author: HUANG Dan-Feng; E-mail: hdf@sjtu.edu.cn; Tel: 021-34206943

Abstract:

Melon potassium channel MIRK, after heterologous expression in Xenopus laevis oocytes was found an inhibition by external Na⁺. In order to investigate the effect of external Na⁺ on MIRK and explore the molecular base of blockage site(s), we proceeded our research by performing site-directed mutagenesis experiment after amino acid align and obtained three mutants of MIRK, then, used double electrode voltage clamp techniques as a research tool in this study. The results indicated that the depressing effect was not determined by single amino acid but might involve serine, lysine, glutamine combination from 232–234 sites and asparagines at a 241-site.

Key words: melon potassium channel MIRK; mutant; external Na⁺; inhibition; electrophysiology