The role of translational product from avirulent genes in xanthomonads bacteria after traficking into plant nuclei.

黄单胞菌无毒基因翻译产物进入植物细胞核后的作用。

基本信息

批准号：
09460026
负责人：
TSUYUMU Shinji
金额：
$ 2.69万
依托单位：
Shizuoka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1999
项目状态：
已结题

项目摘要

It has been known that avr/pthA gene family of Xanthomonads bacteria induce either resistant reactions or disease development. Since they are highly homologous each other, the basic mechanisms involved in both reactions of plants may be common. This study is to find out the initial event of both reactions using molecular biological analyses. Using Xanthomonas citri, a causal agent of citrus canker, as the model system, we have cloned three pthA homologues, and found that only one of them has the ability of causing canker symptom. Comparison of the sequences of these homologues showed that they showed complete homology except in the tandemly repeating region within their genes. Thus, this region was shown to be responsible for the formation of canker symptom on citrus plant, and the importance of the secondary structure was also shown to be important. After overexpression of pthA in E. coli using expression vector, the purified protein was used for affinity chromatography to isolate its receptor protein from citrus leaves. N-terminal amino acid sequence of this receptor protein was determined. Using the mixed oligomer for this peptide was used for the isolation of the gene for the receptor protein. Its nucleotide sequence was determined and it was found to be highly homologous to CCoAMT (S-adenosyl L methionine : trans cafeoryl CoenzymeA 3-O-methyltransferase) of various plants. This enzyme has been shown to be responsible for the lignin after infection with pathogen. Thus, the mechanism for the canker formation on citrus plants was suggested to be due to the alteration in the lignin synthesis which leads to cell elongation.

众所周知，黄黄核细菌的AVR/PTHA基因家族会诱导抗性反应或疾病的发展。由于它们彼此高度同源，因此植物两种反应的基本机制可能很常见。这项研究是通过分子生物学分析来找出两种反应的初始事件。使用柑橘溃疡的因果剂xanthomonas citri作为模型系统，我们克隆了三个PTHA同源物，发现其中只有一个具有引起溃疡症状的能力。这些同源物的序列的比较表明，除了其基因内的串联重复区域外，它们显示出完全的同源性。因此，该区域被证明是导致柑橘植物上溃疡症状形成的原因，并且二级结构的重要性也被证明很重要。使用表达载体在大肠杆菌中过表达PTHA后，将纯化的蛋白用于亲和色谱法将其受体蛋白与柑橘叶分离。确定该受体蛋白的N末端氨基酸序列。使用该肽的混合寡聚物用于分离受体蛋白的基因。确定其核苷酸序列，并发现它与各种植物的CCOAMT（S-腺苷L蛋氨酸：反式咖啡馆3-o-甲基转移酶）同源。该酶已被证明是感染病原体后木质素的原因。因此，建议在柑橘植物上形成的机制是由于木质素合成的改变，导致细胞伸长。