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Inducible reactivation of bacteriophage T7 damaged by methyl methanesulfonate or UV light

L A Dodson, W E Masker

    Journal of Bacteriology
    |October 1, 1983
    PubMed

    Insights

    Host cell SOS response enhances bacteriophage T7 survival after UV or MMS DNA damage. This inducible reactivation is independent of the umuC gene, suggesting broader repair mechanisms are involved.

    Area of Science:

    • Microbiology
    • Molecular Biology
    • Genetics

    Background:

    • Bacterial SOS response is a DNA repair mechanism activated by DNA damage.
    • Bacteriophage T7 survival can be influenced by host cell repair pathways.
    • The umuC gene and plasmid pKM101 are known factors in bacterial DNA repair.

    Purpose of the Study:

    • To investigate the role of SOS-mediated reactivation in bacteriophage T7 survival.
    • To determine the influence of host mutations and UV induction on T7 survival after UV or MMS damage.
    • To assess the umuC dependence of inducible T7 reactivation.

    Main Methods:

    • Assessing survival rates of UV- or MMS-damaged bacteriophage T7.
    • Utilizing host strains with specific mutations (umuC) and plasmids (pKM101).
    • Comparing phage survival on induced (UV-preirradiated) versus non-induced host cells.
    • Examining survival after thermal induction of a dnaB mutant.

    Main Results:

    • Host cell pre-irradiation (SOS induction) significantly enhanced T7 survival after both UV and MMS damage.
    • T7 survival enhancement was proportional to the UV inducing dose and dependent on phage DNA damage.
    • The presence of plasmid pKM101 slightly enhanced UV-irradiated T7 survival, but umuC mutations did not affect MMS-damaged T7 survival.
    • Inducible reactivation of T7 was observed to be independent of the umuC gene.

    Conclusions:

    • Bacterial SOS induction promotes efficient repair of lethal DNA lesions in bacteriophage T7.
    • The inducible reactivation pathway for T7 is not dependent on the umuC gene.
    • Host cell's SOS response plays a crucial role in protecting bacteriophage T7 from DNA-damaging agents like UV light and MMS.

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