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Variability of low-molecular-weight, heat-modifiable outer membrane proteins of Neisseria meningitidis
Abstract:
Analysis of major outer membrane protein (MOMP) profiles of various meningococci by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (SDS-PAGE) revealed the presence of 0 to 2 low-molecular-weight, heat-modifiable MOMPs (molecular weight, 25,000 to 32,000) and 1 to 3 high-molecular-weight MOMPs (molecular weight, 32,000 to 46,000). Heat modifiability was investigated by comparing MOMP profiles after heating in SDS solutions at 100 degrees C for 5 min or at 40 degrees C for 1 h. Low-molecular-weight MOMPs shifted to higher apparent molecular weights after being heated at 100 degrees C. Heat modifiability of high-molecular-weight MOMPs varied among strains; whenever modified these proteins shifted to lower apparent molecular weights after complete denaturation. Variability of low-molecular-weight, heat-modifiable MOMPs was demonstrated when MOMP profiles were compared of (i) isolates from index cases and associated cases and carriers among contacts, (ii) different isolates from the same individual, and (iii) isolates from a small epidemic caused by serogroup W-135. In some cases high-molecular-weight MOMPs revealed quantitative differences among related strains. The observed variability and quantitative differences indicate that MOMP serotyping and typing on the basis of SDS-PAGE profiles (PAGE typing) need careful reevaluation.
Insights
Analysis of meningococcal major outer membrane proteins (MOMPs) using SDS-PAGE reveals significant variability. This heat modifiability and quantitative differences suggest PAGE typing needs reevaluation for accurate meningococcal characterization.
Area of Science:
- Microbiology
- Proteomics
- Molecular Biology
Background:
- Neisseria meningitidis (meningococcus) is a significant human pathogen.
- Major outer membrane proteins (MOMPs) are key targets for bacterial typing and vaccine development.
- Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) is a common method for analyzing protein profiles.
Purpose of the Study:
- To analyze the major outer membrane protein (MOMP) profiles of various meningococci.
- To investigate the heat modifiability of MOMPs and its implications for protein characterization.
- To assess the variability of MOMP profiles within and between meningococcal strains.
Main Methods:
- Analysis of MOMP profiles using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE).
- Comparison of MOMP profiles after differential heat treatment (100°C for 5 min vs. 40°C for 1 h).
- Evaluation of MOMP profiles from various isolates, including those from cases, contacts, and epidemic strains.
Main Results:
- Meningococci possess 0-2 low-molecular-weight (25-32 kDa) and 1-3 high-molecular-weight (32-46 kDa) MOMPs.
- Low-molecular-weight MOMPs exhibited heat modifiability, shifting to higher apparent molecular weights after high-temperature heating.
- High-molecular-weight MOMPs showed variable heat modifiability, shifting to lower apparent molecular weights upon complete denaturation.
- Significant variability in low-molecular-weight MOMPs was observed across different isolates and epidemiological contexts.
- Quantitative differences in high-molecular-weight MOMPs were noted among related strains.
Conclusions:
- Meningococcal MOMP profiles display considerable variability, particularly in low-molecular-weight, heat-modifiable proteins.
- Heat modifiability of MOMPs is a complex phenomenon that differs between low and high-molecular-weight proteins.
- The observed variability and quantitative differences challenge the reliability of current MOMP serotyping and SDS-PAGE-based typing (PAGE typing) methods.
- Reevaluation of MOMP serotyping and PAGE typing strategies is necessary for accurate meningococcal strain characterization.