Hopkins K B, Chapman L F, Temeyer K B
Division of Biological Sciences, University of Missouri, Columbia 65201.
SAAS Bull Biochem Biotechnol. 1990 Jan;3:69-73.
The Bacillus subtilis plasmid pKBT1, the product of in vivo recE4-independent recombinal events, contains segments derived from pUB110 and the B. subtilis chromosome. To determine whether the pUB110 sequence is intact in PKBT1, two 1 kb fragments, each containing a site at which chromosomal and pUB110 sequences are joined, were cloned and sequenced. Sequencing data revealed that: 1). An intact copy of pUB110 is present in pKBT1; 2) The apparent recombination sites were adjacent to the Bam HI-generated ends of pUB110 sequences; 3) pTL12-derived sequences from the original transforming DNA were limited to no more than 1 bp outside the Bgl II recognition sequence; 4) Recombination sites at both ends of pUB110 contain a 19 bp inverted repeat with 15 homologous nucleotides. These findings suggest a site-specific mechanism acting during in vivo formation of pKBT1.
枯草芽孢杆菌质粒pKBT1是体内非recE4依赖性重组事件的产物，它包含来自pUB110和枯草芽孢杆菌染色体的片段。为了确定pUB110序列在PKBT1中是否完整，克隆并测序了两个1 kb片段，每个片段都包含一个染色体和pUB110序列连接的位点。测序数据显示：1）pKBT1中存在pUB110的完整拷贝；2）明显的重组位点与pUB110序列的Bam HI产生的末端相邻；3）来自原始转化DNA的pTL12衍生序列在Bgl II识别序列外不超过1 bp；4）pUB110两端的重组位点包含一个19 bp的反向重复序列，有15个同源核苷酸。这些发现表明在pKBT1的体内形成过程中存在一种位点特异性机制。
