An existence of cold stable vacuolar H^+-ATPase in Plants and its structural properties.

植物冷稳定液泡H^-ATP酶的存在及其结构特性。

基本信息

批准号：
05454012
负责人：
YOSHIDA Shizuo
金额：
$ 4.29万
依托单位：
The Institute of Low Temperature Science Hokkaido University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1994
项目状态：
已结题

项目摘要

The cold stability of vacuolar H^+-ATPase in vivo is markedly different between mung bean (Vigna radiata L.) and pea (Pisum sativum L.), the plants which are representatives of cold-sensitive and cold-tolerant species, respectively. Upon cold exposure of mung bean seedlings the H^+-ATPase activity declined significantly soon after the start of the cold treatment. In pea seedlings, by contrast, the H^+-ATPase remained highly active for long periods of the cold treatment. On cold incubation of isolated vacuolar membranes in vitro in the presence of MgATP and chaotropic anions such as C1^-, NO^-_2 and NO^-_3, the vacuolar H^+-ATPases exhibited also a marked difference in the cold-induced destabilization between these plants, especially in the sensitivity to the concentration of the anions. The enzyme from mung bean appeared to be more susceptible to the anions, particularly to NO^-_2, than the enzyme from pea, resulting in more severe cold-inactivation at the lower concentrations. The MgATP-dependent cold inactivation of the H^+-ATPase was closely associated with a release of the peripheral sectors from the membranes in the same way as in vacuolar-type H^+-ATPases from wide range of organisms. Thus, the cold stability of the enzyme complex both in vivo and in vitro is considered to be dependent on the intrinsic properties of the enzyme, suggesting the existence of "cold-labile" and "cold-stable" types in plants. SDS-PAGE and immunoblot analysis of the subunit components of the H^+-ATPase from both plants revealed that the molecular structures, especially the epitopes of the membrane sectors (16kD), differ each other, albeit that the molecular masses of other minor subunits are also slightly different. These findings in the present study are considered to provide a new insight into the mechanism to control the cold stability of vacuolar H^+-ATPase in plants.

在体内液泡H^+ATPase的冷稳定性在Mung Bean（Vigna radiata L.）和Pea（Pisum sativum L.）之间是明显不同的，这些植物分别是冷敏感和耐冷耐受性物种的植物。绿豆幼苗冷暴露后，H^+ - ATPase活性在冷治疗开始后不久就会显着下降。相比之下，在豌豆幼苗中，在冷处理的长时间内，H^+ATPase保持高度活跃。在MGATP和Chaotropic阴离子存在的情况下，在体外冷孵育时，例如C1^ - ，NO^-_ 2和NO^ - _ 3，液泡H^+ATPases在冷诱导的差异也显示出很明显的差异这些植物之间的不稳定，尤其是对阴离子浓度的敏感性。来自绿豆的酶似乎比豌豆的酶更容易受到阴离子的影响，尤其是^-_ 2，从而导致较低浓度下的冷冷输液更严重。 H^+ATPase的MGATP依赖性冷灭活与从膜上释放的外围部门的释放与液泡型H^+ATP酶相同。因此，体内和体外的酶复合物的冷稳定性都被认为取决于酶的内在特性，这表明植物中存在“冷babile”和“冷稳定”类型。来自两种植物的H^+ATPase的亚基成分的SDS-PAGE和免疫印迹分析表明，分子结构，尤其是膜扇区的表位（16kD）的表位，彼此之间有所不同，虽然是其他次要亚基的分子质量也略有不同。本研究中的这些发现被认为是对控制植物中液泡H^+ATPase的冷稳定性的机制的新见解。