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Studies on the structure and rearrangements of the linear chromosome of Streptomyces griseus 2247.

灰色链霉菌2247线性染色体结构和重排的研究。

基本信息

批准号：
09460050
负责人：
KINASHI Haruyasu
金额：
$ 8.06万
依托单位：
HIROSHIMA 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 1998
项目状态：
已结题

项目摘要

The structure of the linear chromosome of Streptomyces griseus strain 2247 and its dynamic rearrangements have been studied on molecular level, and the following results were obtained.1. The nucleotide sequence of the chromosomal end of S.griseus 2247 was determined and compared with those of other Streptomyces linear chromosomes and plasmids. The conserved end sequence was not found there but several inverted repeats were. These sequences may form hairpin loops and function in replication of the linear DNA.2. Many deletion mutants have been prepared by UV-irradiation of strain 2247. The relationship between the deletion size and topology of the mutant chromosomes suggests that some region near the afsA gene on the left side of the chromosome is essential for maintenance of the linear chromosome.3. The fusion junctions of the circularized chromosomes in three mutants, 404-23, N2 and 83, were cloned and sequenced. The chromosomal circularization was deduced to occur by illegitimate recombination between the right and left deletion ends which do not have any homology to each other.4. Only the mutant 301-22 keeps a linear chromosome. Complicated rearrangements were found to have occurred on its chromosome. Namely, the right arm of the chromosome was replaced by the left arm, and additionally a new fragment was attached to both deletion ends of the chromosome.

对灰色链霉菌2247菌株的线性染色体结构及其动态重排进行了分子水平的研究，得到了以下结果： 1．测定了S.griseus 2247染色体末端的核苷酸序列，并与其他链霉菌线性染色体和质粒的核苷酸序列进行了比较。那里没有发现保守的末端序列，但发现了几个反向重复序列。这些序列可以形成发夹环并在线性DNA的复制中发挥作用。2．菌株2247经紫外照射已制备出多种缺失突变体。突变体染色体的缺失大小与拓扑结构之间的关系表明，染色体左侧afsA基因附近的某些区域对于维持线性染色体至关重要。 3．对 404-23、N2 和 83 三个突变体中环状染色体的融合连接点进行了克隆和测序。推测染色体环化是由于左右缺失端之间的非法重组而发生的，而左右端之间没有任何同源性。 4．只有突变体301-22保留了线性染色体。人们发现其染色体上发生了复杂的重排。即，染色体的右臂被左臂取代，并且另外一个新片段被附着到染色体的两个缺失端。