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Quantitative immunoelectrophoretic analysis of Streptococcus pyogenes membrane
Abstract:
The antigenic composition and molecular structure of the plasma membrane of Streptococcus pyogenes (group A; M type 6) were studied by crossed immunoelectrophoresis (XIE) and other related quantitative immunoelectrophoretic techniques. After establishment of a reference pattern of 29 immunoprecipitates, the relative differences in amounts of individual antigens contained in membranes isolated from cells that were harvested during the exponential or stationary phase of growth were examined. Relative increases and decreases in amounts of individual antigens were estimated from the areas subtended by immunoprecipitates after XIE of Triton X-100 extracts. The asymmetric distribution of antigens on the inner and outer surfaces of the membrane was established in absorption experiments with intact, stable protoplasts. Of the 29 immunoprecipitates, 8 appeared to contain antigens exposed on the outer surface of the membrane, whereas 11 appeared to contain antigens either located on the inner surface or unexposed. Six antigens appeared to have limited exposure on the outer surface, and four others remain to be assigned. Certain immunoprecipitates were characterized with respect to enzymatic activity or interaction with the lectin concanavalin A. Reduced nicotinamide adenine dinucleotide dehydrogenase (EC 1.6.99.3), adenosine triphosphatase (EC 3.6.1.3), and polynucleotide phosphorylase (EC 2.3.7.8) were demonstrated by zymogram techniques. The latter two activities were present within the same immunoprecipitate, suggesting the occurrence of a multienzyme complex. In addition, the areas under the immunoprecipitates containing the three enzymatic activities were not affected by absorption of antimembrane immunoglobulin with intact protoplasts and thus appeared to be located on the inner surface of the membrane. The results from absorption experiments also suggested that the exposure of outer protoplast surface antigens was greater on protoplasts from exponential-phase cells than on those from stationary-phase cells, even when found in increased amounts in the latter.
Insights
This study investigated Streptococcus pyogenes plasma membrane antigens using quantitative immunoelectrophoresis. Researchers identified antigen distribution and enzymatic activities, revealing differences between growth phases and membrane surfaces.
Area of Science:
- Microbiology
- Immunology
- Molecular Biology
Background:
- Streptococcus pyogenes is a significant human pathogen.
- Understanding its cell envelope is crucial for developing targeted therapies.
- Plasma membrane antigen composition and localization are key to bacterial-host interactions.
Purpose of the Study:
- To characterize the antigenic composition and molecular structure of Streptococcus pyogenes plasma membranes.
- To investigate the distribution of membrane antigens on inner and outer surfaces.
- To examine antigen expression changes during different growth phases.
Main Methods:
- Crossed immunoelectrophoresis (XIE) and quantitative immunoelectrophoretic techniques.
- Zymogram techniques to identify enzymatic activities.
- Absorption experiments using intact protoplasts to determine antigen localization.
Main Results:
- A reference pattern of 29 immunoprecipitates was established for Streptococcus pyogenes membranes.
- Antigen distribution was asymmetric, with specific antigens located on inner, outer, or both surfaces.
- Enzymatic activities (Reduced nicotinamide adenine dinucleotide dehydrogenase, Adenosine triphosphatase, Polynucleotide phosphorylase) were identified, with some suggesting a multienzyme complex.
- Outer surface antigen exposure was higher in exponential-phase cells compared to stationary-phase cells.
Conclusions:
- The study provides a detailed molecular map of the Streptococcus pyogenes plasma membrane.
- Differential antigen exposure suggests distinct roles in bacterial physiology and host interaction.
- Enzymatic activities localized to the inner membrane indicate specific metabolic functions within the cell envelope.