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The nature of colicin K from Proteus mirabilis

M A Jesaitis

    The Journal of Experimental Medicine
    |May 1, 1970
    PubMed

    Insights

    Colicinogenic factor K was transferred from E. coli to Proteus mirabilis, yielding a purified colicin K protein. This protein, a low molecular weight bacteriocin, was separated into two components with identical biological properties but different charges.

    Area of Science:

    • Microbiology
    • Molecular Biology
    • Biochemistry

    Background:

    • Colicinogenic factor K (Col K) is a genetic element conferring the ability to produce colicins.
    • Transferring Col K between bacterial species can reveal insights into its genetic structure and protein expression.
    • E. coli K 235 is a known producer of colicin K.

    Purpose of the Study:

    • To transfer the colicinogenic factor K from E. coli K 235 to Proteus mirabilis.
    • To characterize the resulting colicin K produced by Proteus mirabilis.
    • To investigate the properties of the purified bacteriocin.

    Main Methods:

    • Bacterial conjugation for genetic transfer.
    • Mitomycin C induction for colicin secretion.
    • Chromatography for protein purification.
    • Immunological assays for homogeneity.
    • Amino acid analysis and molecular weight determination.
    • Electrofocusing for component separation.

    Main Results:

    • Successful transfer of Col K to Proteus mirabilis, with DNA analysis indicating a satellite DNA harboring the factor.
    • Proteus mirabilis secretes colicin K upon mitomycin C induction.
    • Purified colicin K is an immunologically homogeneous protein, low in molecular weight, lacking cysteine, lipids, and polysaccharides.
    • Electrofocusing resolved colicin K into two components with identical biological activity but distinct electrical charges.

    Conclusions:

    • The colicinogenic factor K can be stably maintained and expressed in Proteus mirabilis.
    • Purified colicin K from Proteus mirabilis is a distinct protein entity with specific biochemical characteristics.
    • The observed heterogeneity in electrical charge suggests potential post-translational modifications or allelic variations within the colicin K protein.

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