THE F-PLASMID ORIGIN OF TRANSFER - DNA-SEQUENCE OF WILD-TYPE AND MUTANT ORIGINS AND LOCATION OF ORIGIN-SPECIFIC NICKS
THE F-PLASMID ORIGIN OF TRANSFER - DNA-SEQUENCE OF WILD-TYPE AND MUTANT ORIGINS AND LOCATION OF ORIGIN-SPECIFIC NICKS
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DOI：
10.1002/j.1460-2075.1984.tb01947.x
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发表时间：
1984-01-01
期刊：
影响因子：
11.4
通讯作者：
WILLETTS, N
中科院分区：
文献类型：
--
作者：
THOMPSON, R;TAYLOR, L;WILLETTS, N
确定了接合 DNA 转移的 F 质粒起点 oriT 的 DNA 序列。起源位于顺反子间区域，该区域包含多个反向重复序列和长的富含 AT 的区域。在结合DNA复制开始之前将切口引入oriT区中的1条DNA链中，并且链特异性切口的位置由λ获得。确定了在携带 Flac 的细胞中增殖后的 oriT 基因组。这些切口的位置并不独特，而是由 3 个主要位点和多达 20 个次要位点组成的簇：这一观察结果的生物学意义尚不完全清楚。对使 oriT 功能失活的 9 个独立点突变进行了测序，发现改变了位于最右侧（如图所示）主要切口位点 1 侧 14 和 19 bp [碱基对]的 2 个核苷酸位置中的 1 个或其他。这些关键核苷酸可能位于 oriT 核酸内切酶的识别序列中，因为这些位点的突变可以防止 oriT 出现切口。
The DNA sequence of the F plasmid origin of conjugal DNA transfer, oriT, was determined. The origin lies in an intercistronic region which contains several inverted repeat sequences and a long AT-rich tract. Introduction of a nick into 1 of the DNA strands in the oriT region precedes the initiation of conjugal DNA replication, and the position of the strand-specific nicks acquired by a .lambda. oriT genome upon propagation in Flac-carrying cells was determined. The nicks were not uniquely positioned, rather there was a cluster of 3 major and up to 20 minor sites: the biological significance of this observation is not yet fully clear. Nine independent point mutations which inactivate oriT function were sequenced and found to alter 1 or other of 2 nucleotide positions which lie 14 and 19 bp [base pair] to 1 side of the rightmost (as drawn) major nick site. These key nucleotides may lie in a recognition sequence for the oriT endonuclease, since mutations at these sites prevent nicking at oriT.