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Updated: Dec 25, 2025
Deciphering the Molecular Mechanism and Function of Pore-Forming Toxins Using Leishmania major
Published on: October 28, 2022
Exploiting species specificity to understand the tropism of a human-specific toxin
K M Boguslawski1, A N McKeown2, C J Day3
1Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA.
Abstract:
Many pathogens produce virulence factors that are specific toward their natural host. Clinically relevant methicillin-resistant Staphylococcus aureus (MRSA) isolates are highly adapted to humans and produce an array of human-specific virulence factors. One such factor is LukAB, a recently identified pore-forming toxin that targets human phagocytes by binding to the integrin component CD11b. LukAB exhibits strong tropism toward human, but not murine, CD11b. Here, phylogenetics and biochemical studies lead to the identification of an 11-residue domain required for the specificity of LukAB toward human CD11b, which is sufficient to render murine CD11b compatible with toxin binding. CRISPR-mediated gene editing was used to replace this domain, resulting in a "humanized" mouse. In vivo studies revealed that the humanized mice exhibit enhanced susceptibility to MRSA bloodstream infection, a phenotype mediated by LukAB. Thus, these studies establish LukAB as an important toxin for MRSA bacteremia and describe a new mouse model to study MRSA pathobiology.
Insights
Researchers identified a key domain in the Staphylococcus aureus toxin LukAB responsible for targeting human cells. This discovery led to a "humanized" mouse model, enhancing susceptibility to MRSA infections for better study.
Area of Science:
- Microbiology
- Immunology
- Genetics
Background:
- Pathogens often possess host-specific virulence factors.
- Methicillin-resistant Staphylococcus aureus (MRSA) is adapted to humans, producing human-specific toxins like LukAB.
- LukAB is a pore-forming toxin targeting human phagocytes via CD11b, showing strong human tropism.
Purpose of the Study:
- To identify the domain responsible for LukAB's human CD11b specificity.
- To develop a "humanized" mouse model for studying MRSA pathobiology.
- To establish LukAB's role in MRSA bloodstream infections.
Main Methods:
- Phylogenetic and biochemical analyses to pinpoint the specificity domain.
- CRISPR-mediated gene editing to create "humanized" mice with modified CD11b.
- In vivo infection studies using the humanized mouse model.
Main Results:
- An 11-residue domain critical for LukAB's human CD11b binding was identified.
- This domain was sufficient to confer toxin binding compatibility to murine CD11b.
- Humanized mice showed increased susceptibility to MRSA bloodstream infection, mediated by LukAB.
Conclusions:
- LukAB is a significant virulence factor in MRSA bacteremia.
- The identified domain is key to LukAB's host specificity.
- The developed humanized mouse model is valuable for MRSA research.
