Stanisich V A, Ortiz J M
J Gen Microbiol. 1976 Jun;94(2):281-9. doi: 10.1099/00221287-94-2-281.
The properties of four P-group plasmids, R26, R527, R751 and R906, which differ in resistance phenotype or in the bacterial species in which they were first detected, have been compared with the prototype of this group, RPI. Two of the plasmids, R26 and R527, are new isolates which have been assigned to the P group because of their incompatibility with R751. The properties studied include response to aeruginocin and to male and female sex-specific phages, interaction with prophage B3 and fertility inhibition by plasmid R38. Strains harbouring these plasmids behaved similarly in all tests except those involving aeruginocin. This suggests that the locus for aeruginocin-insensitivity is one of the R-determinants whereas the genes controlling the remaining characteristics are closely linked to the transfer factor. These plasmids may therefore have a common ancestor and their differences in resistance phenotype may simply reflect recombination events which they have undergone subsequently. Their similarity is also seen in transduction experiments, since determinants from two of these plasmids can be 'rescued' by the P-group plasmid R18 if this is already present in the recipient cell and the host recombination system is functional.
四种P群质粒R26、R527、R751和R906，它们在抗性表型或首次检测到它们的细菌种类上有所不同，已与该群的原型质粒RPI进行了比较。其中两种质粒R26和R527是新分离株，由于它们与R751不兼容而被归为P群。所研究的特性包括对绿脓菌素、雄性和雌性特异性噬菌体的反应、与原噬菌体B3的相互作用以及质粒R38对育性的抑制。除了涉及绿脓菌素的测试外，携带这些质粒的菌株在所有测试中的表现都相似。这表明对绿脓菌素不敏感的位点是R决定簇之一，而控制其余特性的基因与转移因子紧密相连。因此，这些质粒可能有一个共同的祖先，它们在抗性表型上的差异可能仅仅反映了它们随后经历的重组事件。在转导实验中也可以看到它们的相似性，因为如果受体细胞中已经存在P群质粒R18且宿主重组系统功能正常，那么来自其中两种质粒的决定簇可以被R18 “拯救”。
