Amster O, Zamir A
FEBS Lett. 1986 Mar 3;197(1-2):93-8. doi: 10.1016/0014-5793(86)80305-2.
Electrophoretic resolution of topoisomers was used to compare the in vivo superhelicity of recombinant plasmids containing a fragment of cDNA for an immunoglobulin light chain, cloned in the two possible orientations into the BamHI site of pBR313 or pBR322. Previously, frequent transpositions of IS1 or IS5 were observed into the sequence upstream to the cloned fragment in recombinants in one orientation [(+) plasmids] but not in recombinants in the opposite, (-) orientation [(1982) Nucleic Acids Res. 10, 4525-4542]. The results of the present analyses show that, on average, (-) plasmids are less negatively supercoiled than (+) plasmids, or pBR322. These results suggest that primary sequence rearrangements in plasmids could affect their in vivo topological state, and consequently, perhaps, their effectiveness as recipients of transposable elements.
采用拓扑异构体的电泳分辨率来比较重组质粒的体内超螺旋状态，这些重组质粒含有免疫球蛋白轻链cDNA片段，以两种可能的方向克隆到pBR313或pBR322的BamHI位点。以前，在一种方向的重组体（(+)质粒）中，观察到IS1或IS5频繁转座到克隆片段上游的序列中，但在相反方向（(-)方向）的重组体中则没有（(1982)《核酸研究》10, 4525 - 4542）。目前的分析结果表明，平均而言，(-)质粒的负超螺旋程度低于(+)质粒或pBR322。这些结果表明，质粒中的一级序列重排可能会影响其体内拓扑状态，因此，也许还会影响其作为转座元件受体的有效性。
