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Isolation and partial properties of a porin-like protein from Vibrio parahaemolyticus cell envelope

T Koga, T Kawata

    Microbiology and Immunology
    |January 1, 1983
    PubMed

    Insights

    Researchers identified a major 35,000-molecular-weight protein in the Vibrio parahaemolyticus cell envelope. This porin-like protein is resistant to standard solubilization and enzymatic digestion, suggesting unique structural properties.

    Area of Science:

    • Microbiology
    • Molecular Biology
    • Protein Chemistry

    Background:

    • Vibrio parahaemolyticus is a significant marine bacterium.
    • The cell envelope's protein composition is crucial for bacterial function and interaction.
    • Understanding outer membrane proteins aids in developing targeted antimicrobial strategies.

    Purpose of the Study:

    • To characterize a major, unusual protein found in the Vibrio parahaemolyticus pilot strain K-11 cell envelope.
    • To investigate the protein's resistance to solubilization and enzymatic degradation.
    • To determine the protein's potential classification and structural similarities to known proteins.

    Main Methods:

    • Extraction of the protein from the sodium dodecyl sulfate (SDS)-insoluble fraction of the cell envelope using SDS with 0.4 M NaCl.
    • Purification of the protein via acetone precipitation and gel filtration chromatography.
    • Analysis of protein dissociation and molecular weight using SDS-polyacrylamide gel electrophoresis (SDS-PAGE) at varying temperatures.
    • Amino acid composition analysis.

    Main Results:

    • A major protein with an apparent molecular weight of 35,000 was identified in the Vibrio parahaemolyticus K-11 cell envelope.
    • This protein exhibited resistance to solubilization by 2% SDS at 50°C for 30 minutes and was also resistant to trypsin digestion.
    • The protein was successfully extracted and purified, dissociating into a 35,000-molecular-weight monomer in SDS at 60°C.
    • Amino acid composition analysis revealed significant similarities to porins found in Escherichia coli and Salmonella typhimurium.

    Conclusions:

    • The identified protein is likely a porin or a porin-like protein due to its structural and compositional characteristics.
    • Its resistance to SDS and trypsin suggests a unique and stable structure within the Vibrio parahaemolyticus cell envelope.
    • Further research into this porin-like protein could offer insights into Vibrio parahaemolyticus outer membrane structure and function.

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