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Adherence epitopes of Mycoplasma genitalium adhesin
1Department of Microbiology and Hygiene, Institute for Medical Microbiology and Hygiene, Freiburg, Germany.
Abstract:
The adherence-mediating sites of the 153 kDa adhesin of Mycoplasma genitalium (MgPa-protein) were characterized at the amino acid sequence level using six monoclonal anti-MgPa antibodies which showed adherence-inhibiting activity. For characterization of the regions to which antibody bound, three segments of the adhesin (N-terminal region, a D1-domain located approximately in the middle of the molecule and a D2-domain located near to the C-terminus) were synthesized as overlapping octapeptides. These regions were chosen in analogy to the three domains of Mycoplasma pneumoniae that are involved in the adhesion process. Whereas two monoclonal antibodies (mAb 5B11 and mAb 6F3) bound exclusively to an epitope in the N-region, mAb 3B7 and mAb 6A2 reacted with two distinct epitopes of the D2-domain only. Binding to short synthetic peptides of different regions was analysed for mAb 3A12 (N-region and D1-region) and mAb 2B6 (N-region and D2-region). Close proximity of the N-region and the D2-region in the native MgPa-protein of M. genitalium was indicated in a competitive ELISA test, using freshly harvested M. genitalium cells. Epitope mapping and competition experiments with monoclonal anti-MgPa antibodies revealed interesting differences in the adherence-mediating sites of MgPa and the adhesin (P1-protein) of M. pneumoniae. Whereas a three-dimensional arrangement of protein loops is suggested for both native adhesins, the MgPa-protein and the P1-protein adherence-mediating epitopes are located in non-homologous regions of these two related proteins.(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
Monoclonal antibodies identified specific binding sites on the Mycoplasma genitalium adhesin protein (MgPa-protein). These adherence-mediating sites differ from those in Mycoplasma pneumoniae, despite structural similarities.
Area of Science:
- Microbiology
- Molecular Biology
- Immunology
Background:
- Mycoplasma genitalium adhesin protein (MgPa-protein) mediates adherence.
- Understanding MgPa-protein's adherence sites is crucial for therapeutic strategies.
- MgPa-protein shares similarities with Mycoplasma pneumoniae P1-protein.
Purpose of the Study:
- Characterize the adherence-mediating sites of the MgPa-protein at the amino acid sequence level.
- Identify specific epitopes recognized by adherence-inhibiting monoclonal antibodies.
- Compare the adherence-mediating sites of MgPa-protein with M. pneumoniae P1-protein.
Main Methods:
- Synthesized overlapping octapeptide segments of MgPa-protein (N-terminal, D1, D2 domains).
- Utilized six monoclonal anti-MgPa antibodies with adherence-inhibiting activity.
- Performed epitope mapping using ELISA and competitive binding assays on M. genitalium cells.
Main Results:
- Two antibodies (mAb 5B11, mAb 6F3) bound exclusively to the N-region.
- Two antibodies (mAb 3B7, mAb 6A2) bound exclusively to distinct epitopes in the D2-domain.
- Antibodies mAb 3A12 and mAb 2B6 recognized epitopes in both N-region/D1 and N-region/D2, respectively.
- Competitive ELISA indicated close proximity of N-region and D2-region in native MgPa-protein.
- Epitope mapping revealed non-homologous locations of adherence-mediating sites between MgPa-protein and P1-protein.
Conclusions:
- The N-terminal and D2 domains of MgPa-protein contain key adherence-mediating epitopes.
- MgPa-protein and P1-protein exhibit distinct adherence mechanisms despite structural similarities.
- Adherence-mediating epitopes are located in non-homologous regions of these related adhesins.