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Updated: Feb 10, 2026

Deciphering and Imaging Pathogenesis and Cording of Mycobacterium abscessus in Zebrafish Embryos
Published on: September 9, 2015
A highly conserved two-gene operon is crucial for lipoarabinomannan localization, pathogenesis, and cell envelope
Nicholas Campbell-Kruger1, Amir Balakhmet1, Sarah A Stanley1
1Division of Immunology and Pathogenesis, Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, USA.
Abstract:
Mycobacterium abscessus is an emerging threat, causing infections that are difficult to treat due to intrinsic resistance to most antibiotics. Determinants of M. abscessus physiology and pathogenesis remain poorly understood, hampering therapeutic development. Here, we show that in M. abscessus, the lprg-mfs operon is essential for virulence in macrophages and in mice. Loss of lprg-mfs in M. abscessus causes accumulation of the glycolipid lipoarabinomannan (LAM) on the cell surface and in culture supernatant suggesting that this system participates in LAM import. This contrasts with its proposed role in M. tuberculosis where lprg-mfs has been implicated in the export of various lipids. Consistent with altered lipid distribution, the lprg-mfs mutant displays severe defects in mycomembrane permeability, fluidity, and integrity, and expression of mfs alone restores only a subset of these phenotypes, revealing a surprising uncoupling of envelope fluidity and permeability. Using a suppressor screen to further investigate factors that control the distribution of lipoarabinomannan we find that a point mutation in the unannotated gene MAB_0995 can fully or partially complement all deletion mutant phenotypes. Our data also show that lipoarabinomannan in the mycomembrane is dynamically regulated in response to environmental conditions, including hypoxia and macrophage infection. Together, these findings redefine the role of LprG/Mfs in mycobacterial cell envelope homeostasis and reveal unexpected plasticity in mycomembrane lipid regulation in M. abscessus.
Insights
The lprg-mfs operon is crucial for Mycobacterium abscessus virulence and its cell envelope integrity. This study reveals its role in lipoarabinomannan transport, impacting antibiotic resistance.
Area of Science:
- Microbiology
- Molecular Biology
- Pathogenesis
Background:
- Mycobacterium abscessus infections are difficult to treat due to antibiotic resistance.
- The determinants of M. abscessus virulence and physiology are not well understood.
- The lprg-mfs operon's function in M. abscessus remains unclear.
Purpose of the Study:
- To investigate the role of the lprg-mfs operon in M. abscessus virulence and cell envelope homeostasis.
- To understand the mechanism of lipoarabinomannan (LAM) distribution in M. abscessus.
- To identify factors regulating mycomembrane properties.
Main Methods:
- Genetic manipulation of the lprg-mfs operon in M. abscessus.
- Assessment of virulence in macrophage and mouse models.
- Analysis of lipoarabinomannan (LAM) localization and cell envelope characteristics (permeability, fluidity, integrity).
- Suppressor screening to identify complementary genes.
Main Results:
- The lprg-mfs operon is essential for M. abscessus virulence in macrophages and mice.
- Loss of lprg-mfs leads to LAM accumulation on the cell surface and in supernatant, suggesting a role in LAM import.
- The lprg-mfs mutant exhibits defects in mycomembrane permeability, fluidity, and integrity.
- A mutation in MAB_0995 can complement the lprg-mfs deletion phenotypes.
- LAM regulation in the mycomembrane is dynamic and responsive to environmental conditions.
Conclusions:
- The lprg-mfs operon plays a critical role in M. abscessus pathogenesis and cell envelope homeostasis.
- This study redefines the function of LprG/Mfs in mycobacterial lipid transport, contrasting with M. tuberculosis.
- Mycomembrane lipid regulation in M. abscessus is more plastic than previously thought.
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