Molecular analysis of ion transporters in plant and cyanobacteria involved in response to high osmolality

植物和蓝藻中参与高渗透压反应的离子转运蛋白的分子分析

基本信息

批准号：
17380064
负责人：
UOZUMI Nobuyuki
金额：
$ 6.46万
依托单位：
Tohoku University (2006)Nagoya University (2005)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2006
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17380064/
关键词：
osmolality tonoplast HKT positive residue Arabidopsis salt cyanobacteria pH sensor KCO系液泡膜 Na Hアンチポーター AtHKT1 Ktr カリウムナトリウム

项目摘要

1. We have identified the localization of Arabidopsis Na transporter AtHKT1 in plant cells. The specificity of the anti-AtHKT1 antibodies was confirmed. Immunoelectron microscopy using the antibodies demonstrate that AtHKT1 is targeted to the plasma membrane in xylem parenchyma cells in leaves.2. AtHKT1 disruption alleles caused large increases in the Na content of the xylem sap and conversely reduced the Na content of the phloem sap. The athkt1 mutant alleles had a smaller and inverse influence on the K content compared with the Na content to the xylem, suggesting that K transport may be indirectly affected. The expression of AtHKT1 was modulated not only by the concentrations of Na and K but also by the osmolality of non-ionic compounds.3. The conserved Arg near the middle of the M2D segment was essential for the K^+ transport of KtrB. We propose the existence of the salt bridge(s) between the positive residues in the M2D and the conserved negative residues in the pore region, which reduces an electrostatic barrier against cation permeation caused by the positive residue(s) and that stabilizes the transporter configuration.4. Mutation of a conserved His-157 in the second pore loop of KtrB, drastically reduced the activity of the K^+ transporter KtrABE system from Synechocystis PCC 6803. The result suggests that His-157 plays an essential role in the K^+ transport activity of the transporter system.5. H transport activity of one of Synechocystis Na/H transporters was measured using the inverted membrane vesicle of E. coli expressing the protein. We have identified the charged residues essential for the K transport.

1。我们已经确定了拟南芥Na转运蛋白ATHKT1在植物细胞中的定位。确认了抗AthKT1抗体的特异性。使用抗体的免疫电子显微镜表明，ATHKT1靶向叶片中木质部实质细胞中的质膜2。 ATHKT1破坏等位基因导致木质部含量的Na含量大大增加，并相反降低了韧皮部SAP的Na含量。与木质部的Na含量相比，ATHKT1突变等位基因对K含量的影响较小且反比，这表明K传输可能会间接影响。 ATHKT1的表达不仅是由Na和K的浓度调节的，还通过非离子化合物的渗透率调节。3。 M2D段中间附近的保守ARG对于KTRB的K+运输至关重要。我们提出了M2D中的阳性残基与孔区的保守负残基之间存在的盐桥，这减少了由阳性残基引起的阳离子渗透的静电屏障，并稳定转运蛋白构型。4。在KTRB的第二个孔环中，保守的HIS 157的突变大大降低了Sychocystis PCC 6803的K^+转运蛋白Ktrabe系统的活性。结果表明，His-157在转运蛋白系统的K^+转运活性中起着至关重要的作用。5。使用表达蛋白质的大肠杆菌的倒膜囊泡测量了共藻Na/H转运蛋白的H转运活性。我们已经确定了K运输必不可少的充电残基。