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Insertion of a transposon for chloramphenicol resistance into bacteriophage Mu

A I Bukhari, S Froshauer

    Gene
    |July 1, 1978
    PubMed

    Insights

    Researchers isolated bacteriophage Mu mutants with chloramphenicol resistance (cam) transposon insertions. These mutants exhibit a defect in integration, impacting their ability to transduce resistance genes.

    Area of Science:

    • Molecular Biology
    • Microbiology
    • Genetics

    Background:

    • Bacteriophage Mu is a versatile genetic element used in molecular biology.
    • Transposons, such as Tn9 conferring chloramphenicol resistance, are mobile genetic elements.
    • Understanding phage-host interactions and genetic manipulation is crucial in molecular biology.

    Purpose of the Study:

    • To isolate and characterize bacteriophage Mu mutants carrying chloramphenicol resistance (cam) transposon (Tn9) insertions.
    • To investigate the genetic location and functional consequences of these Tn9 insertions within the Mu genome.
    • To elucidate the role of specific Mu DNA regions in replication and integration.

    Main Methods:

    • Isolation of Mu X cam mutants through selection of heat-resistant survivors from a Mucts62, P1cam dilysogen.
    • Characterization of Tn9 insertion sites using restriction enzyme analysis (EcoRI).
    • Assessment of prophage excision and replication capabilities, and transduction efficiency.

    Main Results:

    • Mu X cam mutants were isolated, showing defective prophage behavior with low excision frequencies.
    • Tn9 insertions were localized to the left end of the Mu genome, within a region controlling early replication functions.
    • Precise Tn9 excision could restore wild-type Mu, with varying frequencies observed.
    • Mu X cam prophages replicated with helper phage, but transduction of chloramphenicol resistance was inefficient, indicating a cis-dominant integration defect.

    Conclusions:

    • The isolated Mu X cam mutants possess a cis-dominant defect in integration.
    • Tn9 insertion in specific Mu DNA regions affects early replication and integration functions.
    • These mutants provide a tool for studying bacteriophage Mu integration mechanisms and gene regulation.

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