Veltkamp E, van de Pol H, Stuitje A R, van den Elzen P J, Nijkamp H J
Contrib Microbiol Immunol. 1979;6:111-21.
The replication and genetic constitution of plasmid CloDF13 was studied using mutants of CloDF13 obtained by NTG mutagenesis, insertion of the ampicillin transposon Tn901, or deletion of particular CloDF13 DNA regions. Analysis of the polypeptides encoded by these mutant plasmids enabled us to locate six genes on the CloDF13 physical map. These genes cover about 60% of the coding capacity of CloDF13. A large part of the CloDF13 genome (about 30%) is involved in the conjugal transfer of this plasmid. This transfer region codes for at least two polypeptides, polypeptide B (61,000 daltons) and C (24,000 daltons). Those CloDF13 DNA regions responsible for the synthesis of the cloacin protein and immunity protein were also mapped on the plasmid genome. In addition we were able, using a copy mutant of CloDF13, CloDF13-cop3, to locate those DNA sequences involved in interaction with male-specific RNA phages and bacteriophage P1. For replication of CloDF13, two regions are essential. One region, from 43% to 64%, affects the stability of CloDF13-cop3 plasmids. In the case of the CloDF13-cop3 mutant, deletion of this region results in the generation of multimeric plasmid molecules accompanied by an impaired segregation of plasmid DNA molecules to daughter cells. The second region, from about 1.8% to 11.5%, contains an origin of replication as well as well as DNA sequences involved in the control of CloDF13 replication. The replication of CloDF13 starts at about 3% on the CloDF13 physical map and proceeds unidirectionally counter-clockwise.
利用通过NTG诱变、插入氨苄青霉素转座子Tn901或缺失特定CloDF13 DNA区域获得的CloDF13突变体，研究了质粒CloDF13的复制和遗传组成。对这些突变体质粒编码的多肽进行分析，使我们能够在CloDF13物理图谱上定位六个基因。这些基因覆盖了CloDF13约60%的编码能力。CloDF13基因组的很大一部分（约30%）参与了该质粒的接合转移。这个转移区域编码至少两种多肽，多肽B（61,000道尔顿）和C（24,000道尔顿）。负责合成大肠杆菌素蛋白和免疫蛋白的那些CloDF13 DNA区域也定位在质粒基因组上。此外，我们利用CloDF13的一个复制突变体CloDF13-cop3，定位了那些与雄性特异性RNA噬菌体和噬菌体P1相互作用的DNA序列。对于CloDF13的复制，有两个区域是必不可少的。一个区域，从43%到64%，影响CloDF13-cop3质粒的稳定性。在CloDF13-cop3突变体的情况下，删除该区域会导致多聚体质粒分子的产生，同时质粒DNA分子向子细胞的分离受损。第二个区域，从约1.8%到11.5%，包含一个复制起点以及参与CloDF13复制控制的DNA序列。CloDF13的复制在CloDF13物理图谱上约3%处开始，并沿逆时针方向单向进行。
