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Analysis of the Lipid Composition of Mycobacteria by Thin Layer Chromatography
Published on: April 16, 2021
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Cell wall remodeling-dependent morphotype switch in Mycobacterium avium differentially regulates colonization and
Katie Laschanzky1, Giulia Magri Ribeiro1,2, Rodrigo Sequeira1
1Department of Biology, Lund University, Lund 22362, Sweden.
Summary
The Mycobacterium avium complex switches between transparent (SmT) and opaque (SmO) colony forms. SmO colonization depends on inflammasome activation, while SmT persists independently, explaining its selection in patients.
Area of Science:
- Microbiology
- Immunology
- Genetics
Background:
- Mycobacterium avium complex exhibits two colony morphologies: smooth transparent (SmT) and smooth opaque (SmO).
- SmT is linked to human disease and antimicrobial resistance, but the transition mechanism remains unclear.
- Previous research suggested reversible switching between SmT and SmO forms.
Purpose of the Study:
- To elucidate the mechanism of morphotype transition in Mycobacterium avium.
- To investigate the distinct roles of SmT and SmO morphotypes in host-pathogen interactions during pulmonary infection.
Main Methods:
- Utilized a clinical strain of M. avium ssp hominissuis.
- Integrated phenotypic, genomic, and transcriptomic analyses.
- Performed macrophage infections and murine aerosol instillation models.
Main Results:
- Transparent-to-opaque conversion occurs without genetic rearrangement, linked to peptidoglycan hydrolysis gene deregulation (marP, ripA).
- SmO morphotype activates the NLRP3/ASC inflammasome in macrophages.
- SmO shows increased lung colonization but poor persistence, dependent on inflammasome activation.
- SmT exhibits poor lung colonization but efficient, inflammasome-independent persistence.
Conclusions:
- A cell wall peptidoglycan remodeling-dependent mechanism drives morphotype transition in M. avium.
- Distinct functional roles for SmT and SmO morphotypes exist during pulmonary infection.
- The SmT morphotype's persistence mechanism likely explains its selection in human patients.
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