Conjugational cotransfer of IncFI and IncI conjugative plasmids forming aggregate in a pathogenic Citrobacter freundii strain.
Two plasmids, pEM4 (IncFI) determining virulence and pEM6 (IncI) determining colicine I production and resistance to tetracycline, have been found in a pathogenic strain of Citrobacter freundii. Even though pEM4 and pEM6 plasmids are conjugative and transfer themselves very efficiently during conjugation, a high cotransfer of both plasmids is observed--an unusually high fraction of transconjugants acquiring pEM6 acquires pEM4 and vice versa. The observed cotransfer of these plasmids is connected with their ability to complement their conjugational functions. An insertion mutant of pEM4 with decreased frequency of conjugational transfer has been isolated. This mutant (pEM44) lost its ability to mobilize nonconjugative plasmids. Its transfer is stimulated by pEM6 and it is transferred from (pEM44, pEM6) donors almost exclusively with pEM6 plasmid. The role of cotransfer and stimulation phenomena in spreading of plasmid aggregates in bacterial population is discussed.
Institute of Microbiology, Wrocław University, Poland.
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Morzejko
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Panek
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Cebrat
D003086:Bacteriocin Plasmids; D002954:Citrobacter / Q000235:genetics* / Q000472:pathogenicity; D003227:Conjugation, Genetic / Q000235:genetics*; D004269:DNA, Bacterial; D004926:Escherichia coli / Q000235:genetics; D005798:Genes, Bacterial; D008970:Molecular Weight; D009154:Mutation; D010957:Plasmids; D013753:Tetracycline Resistance / Q000235:genetics; D014774:Virulence / Q000235:genetics
D004269:DNA, Bacterial