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Isolation of Neisseria meningitidis mutants deficient in class 1 (porA) and class 3 (porB) outer membrane proteins
J Tommassen1, P Vermeij, M Struyvé
1Department of Molecular Cell Biology, State University of Utrecht, The Netherlands.
Abstract:
The class 1 major outer membrane protein of Neisseria meningitidis is a serious candidate for a meningococcal vaccine. To facilitate studies on the function of this protein, mutants were isolated that lacked this protein or the structurally related class 3 protein. These mutants were obtained by using the antibody-dependent bactericidal action of the complement system. The class 1 protein-deficient strain grew normally in vitro, whereas growth of the class 3 protein-deficient strain was slightly retarded. The class 3 protein-deficient strain displayed increased resistance to the antibiotics tetracycline and cefsulodin, which is consistent with the proposed role of the protein as a pore-forming protein. The class 1 protein was purified to homogeneity from the class 3 protein-deficient strain. Lipid bilayer experiments revealed that this protein also formed pores. The class 1 protein pores were cation selective.
Insights
Neisseria meningitidis class 1 outer membrane protein, a vaccine candidate, was studied using mutant strains. This protein forms cation-selective pores, similar to the related class 3 protein.
Area of Science:
- Microbiology
- Immunology
- Vaccine Development
Background:
- The class 1 major outer membrane protein of Neisseria meningitidis is a key target for meningococcal vaccine development.
- Understanding the function of outer membrane proteins is crucial for Neisseria pathogenesis and vaccine design.
Purpose of the Study:
- To investigate the functional role of the class 1 major outer membrane protein in Neisseria meningitidis.
- To characterize the pore-forming properties of the class 1 protein.
Main Methods:
- Isolation of Neisseria meningitidis mutants lacking class 1 or class 3 outer membrane proteins using antibody-dependent complement-mediated bactericidal assays.
- In vitro growth analysis of mutant strains.
- Purification of the class 1 protein.
- Lipid bilayer experiments to assess pore formation.
Main Results:
- Class 1 protein-deficient strains grew normally, while class 3 deficient strains showed slightly retarded growth.
- Class 3 protein-deficient strains exhibited increased resistance to tetracycline and cefsulodin, supporting its pore function.
- Purified class 1 protein was shown to form cation-selective pores in lipid bilayer experiments.
Conclusions:
- Both class 1 and class 3 outer membrane proteins of Neisseria meningitidis possess pore-forming capabilities.
- The class 1 protein's pore-forming activity, specifically its cation selectivity, warrants further investigation for vaccine development.