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Updated: Aug 18, 2026
Identification of Antibacterial Immunity Proteins in Escherichia coli using MALDI-TOF-TOF-MS/MS and Top-Down Proteomic Analysis
Published on: May 23, 2021
Surface proteins of Mycoplasma hyopneumoniae identified from an Escherichia coli expression plasmid library
Abstract:
A genomic library of Mycoplasma hyopneumoniae was constructed by cloning random DNA fragments approximately 300 base pairs long in a fusion expression plasmid, pEx29, containing the N terminus of the phage MS2 polymerase under the control of the PL promoter of phage lambda. Clones that produced fusion proteins carrying surface-specific antigenic determinants were identified by using antiserum raised in a pig by intranasal inoculation of viable mycoplasmas. Rabbit antisera produced against gel-purified fusion proteins synthesized in Escherichia coli were analyzed by Western blotting to identify antigenically related mycoplasma components. Distinct mycoplasma proteins termed P90, P68, P50, P30, and P26 were identified. Evidence for the surface location of P90, P68, and P50 was provided by their sensitivity to trypsin and their comigration with lactoperoxidase-catalyzed iodinated proteins of intact mycoplasmas. Immune electron microscopy, performed with antiserum against the hybrid MS2-mycoplasma protein produced in E. coli and corresponding to P90, also showed that its antigenic determinant is associated with the mycoplasma surface.
Insights
Researchers identified key surface proteins of Mycoplasma hyopneumoniae, including P90, P68, and P50. These proteins are crucial for understanding the bacterium
Area of Science:
- Bacteriology
- Molecular Biology
- Immunology
Background:
- Mycoplasma hyopneumoniae is a significant swine pathogen.
- Identifying surface antigens is crucial for developing effective diagnostics and vaccines.
- Genomic library construction allows for the exploration of bacterial protein expression.
Purpose of the Study:
- To construct a genomic library of Mycoplasma hyopneumoniae.
- To identify and characterize surface-specific antigenic determinants of the bacterium.
- To investigate the location and nature of key mycoplasma proteins.
Main Methods:
- Construction of a Mycoplasma hyopneumoniae genomic library in a fusion expression plasmid (pEx29).
- Screening of clones for surface-specific antigenic determinants using pig antiserum.
- Analysis of fusion proteins by Western blotting and immune electron microscopy.
- Proteins identified through sensitivity to trypsin and comigration with iodinated proteins.
Main Results:
- Identification of distinct Mycoplasma hyopneumoniae proteins: P90, P68, P50, P30, and P26.
- Evidence confirming the surface location of P90, P68, and P50 through biochemical and immunological assays.
- Immune electron microscopy confirmed the surface association of an antigenic determinant corresponding to P90.
Conclusions:
- Several Mycoplasma hyopneumoniae proteins, particularly P90, P68, and P50, are located on the bacterial surface.
- These surface proteins represent potential targets for immunological interventions against Mycoplasma hyopneumoniae infections.
- The study provides a foundation for further research into the pathogenesis and control of swine mycoplasmosis.
