Bolivar F, Betlach M C, Heyneker H L, Shine J, Rodriguez R L, Boyer H W
Proc Natl Acad Sci U S A. 1977 Dec;74(12):5265-9. doi: 10.1073/pnas.74.12.5265.
A small (approximately 1100 base pairs) ColE1-type plasmid, pBR345, was constructed from plasmid pMB1 by a series of in vitro recombinant manipulations. Approximately 9% of the supercoiled pBR345 DNA obtained from cultures amplified with chloramphenicol appears to be replicative intermediates with replicating "eye" structures of uniform size. Results obtained from electron microscopy and biochemical analyses have enabled us to localize the origin of replication at the same position as that reported for ColE1. A sequence of 420 nucleotides surrounding this origin has been determined. A comparison between this sequence and the one determined for the origin of replication of ColE1 is presented.
一种小的（约1100个碱基对）ColE1型质粒pBR345，是通过一系列体外重组操作从质粒pMB1构建而成的。从用氯霉素扩增的培养物中获得的超螺旋pBR345 DNA，约9%似乎是具有大小均匀的复制“眼”结构的复制中间体。电子显微镜和生化分析结果使我们能够将复制起点定位在与ColE1报道的相同位置。已经确定了围绕该起点的420个核苷酸的序列。本文给出了该序列与为ColE1复制起点所确定的序列之间的比较。
