Covarrubias L, Cervantes L, Covarrubias A, Soberón X, Vichido I, Blanco A, Kupersztoch-Portnoy Y M, Bolivar F
Gene. 1981 Jan-Feb;13(1):25-35. doi: 10.1016/0378-1119(81)90040-8.
A DNA sequence essential for the R64drd11 + ColK-mediated conjugal transfer of pBR322 has been located in a 540 bp HaeIII fragment (HaeIII-2) between the vegetative origin of replication and the tetracycline resistance (Tcr) gene of this vector. The pBR322 derivatives pBR327 and pBR328 lack this DNA sequence and are not mobilized by conjugation. Two derivatives of pBR328 were constructed by re-inserting the HaeIII-2 fragment in both orientations into the chloramphenicol-resistance gene of the same vector. One orientation of the HaeIII-2 fragment permitted mobilization by conjugation while the opposite orientation prevented mobilization. Further examination of pBR322 and derivatives revealed that the region between the origin of replication and Tcr gene also plays a role in regulating plasmid copy number.
pBR322的R64drd11 + ColK介导的接合转移所必需的一段DNA序列，位于该载体的复制起点和四环素抗性（Tcr）基因之间的一个540 bp的HaeIII片段（HaeIII - 2）中。pBR322的衍生物pBR327和pBR328缺少这段DNA序列，不能通过接合进行转移。通过将HaeIII - 2片段以两种方向重新插入同一载体的氯霉素抗性基因中，构建了pBR328的两个衍生物。HaeIII - 2片段的一个方向允许通过接合进行转移，而相反方向则阻止转移。对pBR322及其衍生物的进一步研究表明，复制起点和Tcr基因之间的区域在调节质粒拷贝数方面也起作用。
