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Implementation of a Permeable Membrane Insert-based Infection System to Study the Effects of Secreted Bacterial Toxins on Mammalian Host Cells
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Implementation of a Permeable Membrane Insert-based Infection System to Study the Effects of Secreted Bacterial Toxins on Mammalian Host Cells

Published on: August 19, 2016

INTRACELLULAR M PROTEIN OF GROUP A STREPTOCOCCUS

E N FOX

    Journal of Bacteriology
    |March 1, 1963
    PubMed

    Insights

    Group A Streptococcus M protein, a heat-labile antigen, was found intracellularly in the cytoplasm and bound to the protoplasmic membrane. This intracellular M protein was not extracted by standard hot acid procedures used for cell wall M protein.

    Area of Science:

    • Microbiology
    • Immunology
    • Cell Biology

    Background:

    • Group A Streptococcus possesses M protein on its cell wall, crucial for virulence.
    • M protein is typically extracted from cell walls using hot acid procedures.
    • The intracellular location and extraction properties of M protein were previously uncharacterized.

    Purpose of the Study:

    • To investigate the presence and location of M protein within Group A Streptococcus cells.
    • To determine if intracellular M protein can be extracted using standard hot acid methods.

    Main Methods:

    • Protoplasts were generated from a type 14 Group A Streptococcus strain.
    • Cells and protoplasts were treated with trypsin and/or hot HCl.
    • Serological techniques, including immunofluorescence with labeled antisera, were used to detect M protein.

    Main Results:

    • A heat-labile M protein antigen was found in soluble form within the cytoplasm of protoplasts.
    • M protein was also detected bound to the protoplasmic membrane.
    • Hot HCl extraction of trypsinized cells or protoplasts did not yield detectable M protein antigen.
    • Immunofluorescence confirmed M antigen association with the membrane of osmotically lysed protoplasts.

    Conclusions:

    • Group A Streptococcus M protein exists intracellularly, associated with the cytoplasm and protoplasmic membrane.
    • Intracellular M protein exhibits different extraction properties compared to cell wall-associated M protein.
    • These findings suggest distinct pools or forms of M protein within the bacterium.
    Keywords:
    BACTERIAL PROTEINSSTREPTOCOCCUS

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