The function and role of telomeric palindrom sequence newly found in tobacco chromosomes

烟草染色体中新发现的端粒回文序列的功能和作用

基本信息

批准号：
06804046
负责人：
YOSHIDA Kazuo
金额：
$ 1.09万
依托单位：
HIROSHIMA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

项目摘要

The increasing DNA and linearlization of genomes (chromosome formation) are fundamental basis for divergence of eukaryotes from prokaryotes during evolution. The telomeres and telomerase are indispensable for eukaryotic linear chromosomes. Unfortunately, little is known the molecular structure of telomeres in plants. In this research project, we have found and sequenced novel RETS (restriction enzymes-resistant high molecular weight telomeric DNA sequences) in tabacco chromosomes. By using RETS as a probe, we characterized the terminal structure of tobacco chromosomal ends. Furthermore, Southern analysis clearly indicates that RETS are spread out all over the tobacco chromosomes. From these results, we have presented a working hypothesis that RETS offer a seed for telomere formation in the repair of chromosomal damages. In order to know functions of telomere, we constructed the first mobilizable YAC (yeast artificial chromosome) in which oriT (origin of transfer) is inserted between two telomeres. This plasmid was successfully transferred from Escherichia coli bacterium into Saccharomyces cerevisae yeast with the help of mob (mobilization) and tra (transfer) genes on a helper plasmid. However, the transconjugant yeasts had not linear YACs but circular YACs although OriT between telomeres was nicked during trans-kingdom conjugation. This indicates that 5'end of linearlized YAC might be blocked or anchored by something like mob protein moiety which locates in a conjugation tube.

基因组的DNA增加和线性化（染色体形成）是真核生物在进化过程中与原核生物发散的基本基础。对于真核线性染色体，端粒和端粒酶是必不可少的。不幸的是，植物中端粒的分子结构知之甚少。在该研究项目中，我们发现并测序了Tabacco染色体中的Nove Nove RET（耐酶的高分子量端粒DNA序列）。通过将RET作为探针，我们表征了烟草末端的末端结构。此外，南部分析清楚地表明，RET散布在烟草染色体上。从这些结果中，我们提出了一个有效的假设，即在修复染色体损伤时，RET为端粒形成提供了种子。为了了解端粒的功能，我们构建了第一个动员YAC（酵母人工染色体），其中orit（转移的起源）在两个端粒之间插入。该质粒在辅助质粒上的BOB（动员）和TRA（动员）和TRA（转移）基因中成功地从大肠杆菌细菌转移到酿酒酵母酵母中。然而，尽管在反式象牙共轭过程中刻有端粒之间的orit，但跨性酵母不是线性YAC，而是圆形YAC。这表明线性化的YAC的5末端可能被放置在结合管中的暴民蛋白部分之类的东西阻塞或锚定。