Analysis of regulation mechanism of chloroplstic ascorbate peroxidase isoenzymes

叶绿体抗坏血酸过氧化物酶同工酶调控机制分析

基本信息

批准号：
10660102
负责人：
SHIGEOKA Shigeru
金额：
$ 2.18万
依托单位：
Kinki University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

项目摘要

To explore the regulation mechanism of chloroplastic ascorbate peroxides (chlAPX) isoenzymes, we studied the following heads,(1) We have previously shown that stromal (sAPX) and thylakoid-bound (tAPX) ascorbate peroxidase isoenzymes of spinach chloroplasts arise from a common pre-mRNA by alternative splicing. To explore the production of mature, functional mRNA encoding chlAPX isoenzymes, mRNA analysis were performed. Four mRNA variants, one form (tAPX-1) for tAPX and three forms (sAPX-I, -II, and -III) for sAPX, were identified. The expression levels of mRNA variants for sAPX and tAPX isoenzymes are in nearly equal quantities throughout the spinach leaves grown under normal conditions.(2) We studied the response of each APX isoenzyme in spinach leaves under stress conditions imposed by high-light intensity, drought, salinity, and applications of paraquat and abscisic acid. The steady-state transcript level of cytosolic APX (cAPX) remarkably increased in response to high-light intensity and paraquat treatment. The cAPX activity increased in parallel with its transcript abundance during high-light intensity. The other isoenzymes showed no significant changes in their transcript an protein levels and activities, except for he gradual decrease in the chlAPX isoenzymes activities.(3) A cDNA clone encoding L-galactono- γ-lactone (GAL) dehydrogenase was isolated from tobacco leaves. The cDNA clone contained the protein of 56,926 Da, preceded by a putative mitochondrial targeting signal. In fact, GAL dehydrogenase was localized in the mitochondria of tobacco cells. GAL dehydrogenase mRNA is expressed in the leaves, stems, and roots in almost equal quantities. The partially purified recombinant enzyme was used for comparative studies on the native enzymes from tobacco and other sources ; The enzymatic properties of recombinant GAL dehydrogenase were similar to those of other GAL dehydrogenases.

为了探索叶绿素的抗坏血酸过氧化物（CHLAPX）同工酶，我们研究了以下头部，（1）表明，基质（SAPX）和类囊体结合（TAPX）抗坏血酸（Tapx）抗坏血酸（Tapx）抗坏血酸过氧化物是从菠菜氯磷酸化的旋转性的，是由菠菜质量细胞出现的，由菠菜质量塑料列出。替代剪接。鉴定出SAPX的mRNA变异水平和TAPX同工酶在正常分区下生长的脊柱叶子几乎是相等的对高光强度的响应增加，而在其他同工酶期间，CAPX活性并行增加了。从烟叶中分离出脱水酶（GAL）部分纯化的酶用于比较烟草和其他来源的S型酶。