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Bacteriophage receptor area of outer membrane protein OmpA of Escherichia coli K-12

R Morona, C Krämer, U Henning

    Journal of Bacteriology
    |November 1, 1985
    PubMed

    Insights

    Researchers identified new mutations in the outer membrane protein A (OmpA) of Escherichia coli, revealing critical sites for T-even-like phage receptor binding. This completes the characterization of the OmpA phage receptor region.

    Area of Science:

    • Microbiology and Molecular Biology
    • Bacteriophage-Host Interactions
    • Protein Structure-Function Relationships

    Background:

    • T-even-like bacteriophages utilize the outer membrane protein A (OmpA) of Escherichia coli as a cellular receptor.
    • Previous studies identified mutations in ompA conferring phage resistance, suggesting specific residues are involved in receptor function.
    • A model proposed that the N-terminal half of OmpA is repeatedly exposed on the cell surface.

    Purpose of the Study:

    • To further characterize the OmpA protein's phage receptor region by analyzing new phage-resistant mutants.
    • To identify additional residues critical for OmpA-mediated bacteriophage binding.
    • To refine the understanding of OmpA's role as a receptor for T-even-like phages.

    Main Methods:

    • DNA sequence analysis of 14 independently isolated, phage-resistant ompA mutants that still synthesize OmpA.
    • Comparison of new mutations with previously identified alterations.
    • Phenotypic analysis, including assessment of conjugation deficiency.

    Main Results:

    • Eight new mutations were identified, including alterations at residues Ile-24, Gly-28, Glu-68, Gly-70, Ser-108, and Gly-154.
    • Mutations at Ile-24 and Gly-28 confirmed the involvement of this region in phage receptor activity.
    • The alteration at Gly-154----Asp resulted in a conjugation-deficient phenotype.

    Conclusions:

    • The study successfully identified seven new critical alterations in the OmpA protein's phage receptor region.
    • The characterization of these new mutations, along with previous findings, suggests a complete mapping of the OmpA phage receptor area.
    • OmpA's N-terminal region is crucial for T-even-like bacteriophage binding.

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