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Plasmids controlling synthesis of hemolysin in Escherichia coli. II. Polynucleotide sequence relationship among

B Royer-Pokora, W Goebel

    Molecular & General Genetics : MGG
    |March 22, 1976
    PubMed

    Insights

    This study reveals that E. coli plasmids, despite similar sizes, are not genetically stable and undergo frequent recombination during conjugation. Some hemolytic plasmids show limited homology to F and Col Ib plasmids.

    Area of Science:

    • Molecular Biology
    • Microbiology
    • Genetics

    Background:

    • Hemolytic wild-type strains of Escherichia coli (E. coli) harbor plasmids of varying molecular weights.
    • These plasmids play a role in bacterial virulence and genetic exchange.

    Purpose of the Study:

    • To investigate the genetic relationships and stability of plasmids isolated from hemolytic E. coli strains.
    • To determine if plasmids of identical size are always homologous and to classify hemolytic plasmids within known plasmid groups.

    Main Methods:

    • Isolation of plasmids with different molecular weights (A, B, C) from E. coli.
    • DNA-DNA hybridization to assess sequence homology between plasmids.
    • Conjugation experiments to observe plasmid behavior in transconjugant strains.

    Main Results:

    • Plasmids A, B, and C share sequence homology, but plasmid A is not a composite of B and C.
    • Plasmids of identical size in donor and transconjugant strains can lose complete nucleotide sequence homology, indicating instability.
    • A stable recombined plasmid (D) was formed from plasmids B and C in a transconjugant.
    • Hemolytic plasmids showed limited homology to F and Col Ib plasmids, suggesting they are not typically F-like or I-like, though one was F-like.

    Conclusions:

    • E. coli plasmids are dynamic genetic entities, undergoing frequent recombination and dissociation during conjugation.
    • Hemolytic plasmids represent diverse genetic groups, with some distinct from common F-like and I-like plasmids.

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