THE INTEGRATED STATE OF THE ROLLING-CIRCLE PLASMID PTB913 IN THE COMPOSITE BACILLUS PLASMID PTB19
THE INTEGRATED STATE OF THE ROLLING-CIRCLE PLASMID PTB913 IN THE COMPOSITE BACILLUS PLASMID PTB19
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DOI：
10.1007/bf00265444
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发表时间：
1992-06-01
期刊：
影响因子：
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通讯作者：
BRON, S
中科院分区：
文献类型：
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作者：
OSKAM, L;HILLENGA, DJ;BRON, S
pTB19 是一种源自嗜热芽孢杆菌属物种的 27 kb 质粒，在 10.6 kb DNA 片段上包含两个滚环型质粒的整合副本。在本研究中，我们分析了 pTB19 中包含滚环质粒 pTB913 的部分以及两个滚环质粒之间的区域。我们发现，在整合状态下，pTB913 的两侧是 55 bp 的同向重复序列，该重复序列复制了复制起始基因 repB 的一部分。由于repB被中断，集成的pTB913无法启动滚环复制。自主复制的 pTB913 是从 pTB19 产生的，可能是通过 55 bp 同向重复序列之间的重组产生的；这是一次罕见的事件。由于第二个整合滚环型质粒也含有非功能性复制起始基因，因此pTB19的复制必须受到RepA决定簇的控制。由 RepA 控制的 Theta 型复制可能是 pTB19 具有高稳定性的原因。在两个整合的滚环质粒之间存在一个开放阅读框（447个密码子），它可以编码未知功能的蛋白质。
pTB19, a 27 kb plasmid originating from a thermophilic Bacillus species, contains integrated copies of two rolling-circle type plasmids on a 10.6 kb DNA fragment. In the present study we analysed the part of pTB19 that contains the rolling-circle plasmid pTB913 and the region in between the two rolling-circle plasmids. We show that, in the integrated state, pTB913 was flanked by a 55 bp direct repeat that duplicated part of the replication initiation gene repB. Since repB was interrupted, the integrated pTB913 could not initiate rolling-circle replication. Autonomously replicating pTB913 was produced from pTB19, probably through recombination between the 55 bp direct repeats; this was a rare event. Since the second integrated rolling-circle type plasmid also contained a non-functional replication initiation gene, replication of pTB19 must be controlled by the RepA determinant. Theta-type replication, controlled by RepA is likely to account for the high stability of pTB19. In between the two integrated rolling-circle plasmids was present an open reading frame (447 codons) which could encode a protein of unknown function.