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Updated: Apr 6, 2026
Visualisation and Quantification of Intracellular Interactions of Neisseria meningitidis and Human α-actinin by Confocal Imaging
Published on: October 24, 2010
Fratricide activity of MafB protein of N. meningitidis strain B16B6
Jesús Arenas1, Vincent de Maat2, Laura Catón3
1Department of Molecular Microbiology, Utrecht University, Padualaan 8, 3584, CH, Utrecht, The Netherlands. J.A.arenasbusto@uu.nl.
Background:
Neisseria meningitidis is an inhabitant of the mucosal surfaces of the human nasopharynx. We recently demonstrated that the secreted meningococcal Two-partner secretion protein A (TpsA) is involved in interbacterial competition. The C-terminal end of the large TpsA protein contains a small toxic domain that inhibits the growth of target bacteria. The producing cells are protected from this toxic activity by a small immunity protein that is encoded by the gene immediately downstream of the tpsA gene. Further downstream on the chromosome, a repertoire of toxic modules, designated tpsC cassettes, is encoded that could replace the toxic module of TpsA by recombination. Each tpsC cassette is associated with a gene encoding a cognate immunity protein.
Results:
Blast searchers using the toxic domains of TpsA and TpsC proteins as queries identified homologies with the C-terminal part of neisserial MafB proteins, which, for the rest, showed no sequence similarity to TpsA proteins. On the chromosome, mafB genes are part of genomic islands, which include cassettes for additional toxic modules as well as genes putatively encoding immunity proteins. We demonstrate that a MafB protein of strain B16B6 inhibits the growth of a strain that does not produce the corresponding immunity protein. Assays in E. coli confirmed that the C-terminal region of MafB is responsible for toxicity, which is inhibited by the cognate immunity protein. Pull-down assays revealed direct interaction between MafB toxic domains and the cognate immunity proteins.
Conclusions:
The meningococcal MafB proteins are novel toxic proteins involved in interbacterial competition.
Insights
Neisseria meningitidis MafB proteins are novel toxic factors used in bacterial competition. These proteins inhibit growth of competing bacteria, with immunity proteins providing self-protection.
Area of Science:
- Microbiology
- Bacterial Pathogenesis
- Molecular Biology
Background:
- Neisseria meningitidis colonizes human nasopharynx.
- Secreted Two-partner secretion protein A (TpsA) mediates interbacterial competition.
- TpsA possesses a toxic C-terminal domain and a cognate immunity protein for self-protection.
Purpose of the Study:
- Investigate novel toxic proteins in N. meningitidis.
- Characterize the role of MafB proteins in interbacterial competition.
Main Methods:
- Bioinformatic analysis (Blast searches) of TpsA and TpsC toxic domains.
- Growth inhibition assays in N. meningitidis and E. coli.
- Protein interaction studies (Pull-down assays).
Main Results:
- Homologies found between TpsA/TpsC toxic domains and MafB proteins.
- MafB proteins are located on genomic islands with associated immunity genes.
- MafB proteins exhibit toxicity mediated by their C-terminal regions.
- Cognate immunity proteins directly interact with MafB toxic domains, neutralizing toxicity.
Conclusions:
- MafB proteins represent a new class of toxic proteins in N. meningitidis.
- These proteins contribute to interbacterial competition through a toxin-antitoxin mechanism.
