PDIM drives the transition from repairable to catastrophic EsxA-mediated vacuole membrane damage during Mycobacterium marinum infection
- 1Department of Biochemistry, Faculty of Science, University of Geneva, Geneva, Switzerland
- 2Institute of Medical Microbiology, Faculty of Medicine, University of Zurich, Zurich, Switzerland
Abstract
During infection, pathogenic mycobacteria damage the membrane of the Mycobacterium-containing vacuole (MCV), triggering host repair responses that preserve an intracellular permissive niche before bacteria escape to the cytosol at later stages. How the MCV transitions from repairable injury to catastrophic rupture remains poorly understood. Here, we dissected the respective contributions of the ESX-1 effectors EsxA/EsxB and the cell-envelope lipid phthiocerol dimycocerosate (PDIM) during Mycobacterium marinum infection of the amoeba Dictyostelium discoideum. Combining host reporters for membrane damage and repair with single and double bacteria mutants, we show that EsxA/EsxB and PDIM are both required for full intracellular virulence but act at distinct stages of MCV damage progression. Loss of EsxA/EsxB strongly reduced recruitment of ESCRT and autophagy reporters to the MCV, demonstrating that EsxA initiates repairable membrane lesions. In contrast, PDIM-deficient bacteria retained the ability to recruit early damage reporters and ESCRT machinery but showed reduced autophagy-associated repair, failed to efficiently acquire cytosolic perilipin coating, and remained largely confined within the MCV. Genetic disruption of host autophagy restored cytosolic access and increased intracellular growth of PDIM-deficient bacteria, indicating that PDIM is specifically required to overcome host repair capacity rather than to initiate damage. Importantly, the sequential requirement for EsxA and PDIM was conserved during infection of murine microglial BV-2 cells. Remarkably, PDIM-defective mutant induced lysenin recruitment, a reporter of sphingomyelin exposure, but progression to autophagy engagement was strongly decreased. Together, our results support a two-step model in which EsxA initiates MCV membrane damage, while PDIM amplifies these lesions towards catastrophic rupture, enabling escape to the cytosol and dissemination. Author summary: Pathogenic mycobacteria, including the agent of tuberculosis, infect host cells and reside in a membrane-delimited compartment. During infection, the membrane of this compartment is damaged, activating host repair mechanisms that initially contain the injury and maintain the bacteria inside the compartment. At later stages, the bacteria escape into the host cell cytosol, allowing the progression of the infection, but how this transition from repairable damage to full membrane rupture occurs is not well understood. Using Mycobacterium marinum infection of amoebae and mammalian cells, we found that two previously characterized bacterial factors act in sequence. EsxA, a secreted bacterial protein, triggers initial membrane damage that can be controlled by host repair systems. In contrast, PDIM, a lipid present at the bacterial surface, allows bacteria to overcome these repair mechanisms and progress toward irreversible membrane disruption. Together, our results show how pathogenic mycobacteria use a two-step process to first induce repairable membrane damage and then bypass host repair systems, enabling escape to the cytosol and successful infection.
Related
- Deciphering the role of TRPML1-mediated calcium homeostasis in innate immune cell responses during Mycobacterium tuberculosis infection
- Diagnostic accuracy of Mycobacterium tuberculosis antigen-induced interferon-γ-inducible protein 10 for latent tuberculosis infection among high-risk groups: a systematic review and meta-analysis
- Loss of Mitochondrial Respiratory Capacity Reshapes Myeloid Cell Function during Mycobacterium tuberculosis infection
- First Report of Mycobacterium bovis and Nocardia spp. Co-Infection in a Roan Antelope
- Functional divergence of regulatory and conventional bovine neutrophils following Mycobacterium bovis infection
BibTeX
@article{michard2026pdim,
title = {{PDIM drives the transition from repairable to catastrophic EsxA-mediated vacuole membrane damage during Mycobacterium marinum infection}},
author = {Céline Michard and Angélique Perret and Mélanie Foulon and Hendrik Koliwer-Brandl and Hubert Hilbi and Thierry Soldati},
journal = {PLOS Pathogens},
year = {2026},
month = oct,
doi = {10.1371/journal.ppat.1014721},
url = {https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1014721},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - PDIM drives the transition from repairable to catastrophic EsxA-mediated vacuole membrane damage during Mycobacterium marinum infection
AU - Céline Michard
AU - Angélique Perret
AU - Mélanie Foulon
AU - Hendrik Koliwer-Brandl
AU - Hubert Hilbi
AU - Thierry Soldati
PY - 2026
DA - 2026/10/21
JO - PLOS Pathogens
DO - 10.1371/journal.ppat.1014721
UR - https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1014721
AB - During infection, pathogenic mycobacteria damage the membrane of the Mycobacterium-containing vacuole (MCV), triggering host repair responses that preserve an intracellular permissive niche before bacteria escape to the cytosol at later stages. How the MCV transitions from repairable injury to catastrophic rupture remains poorly understood. Here, we dissected the respective contributions of the ESX-1 effectors EsxA/EsxB and the cell-envelope lipid phthiocerol dimycocerosate (PDIM) during Mycobacterium marinum infection of the amoeba Dictyostelium discoideum. Combining host reporters for membrane damage and repair with single and double bacteria mutants, we show that EsxA/EsxB and PDIM are both required for full intracellular virulence but act at distinct stages of MCV damage progression. Loss of EsxA/EsxB strongly reduced recruitment of ESCRT and autophagy reporters to the MCV, demonstrating that EsxA initiates repairable membrane lesions. In contrast, PDIM-deficient bacteria retained the ability to recruit early damage reporters and ESCRT machinery but showed reduced autophagy-associated repair, failed to efficiently acquire cytosolic perilipin coating, and remained largely confined within the MCV. Genetic disruption of host autophagy restored cytosolic access and increased intracellular growth of PDIM-deficient bacteria, indicating that PDIM is specifically required to overcome host repair capacity rather than to initiate damage. Importantly, the sequential requirement for EsxA and PDIM was conserved during infection of murine microglial BV-2 cells. Remarkably, PDIM-defective mutant induced lysenin recruitment, a reporter of sphingomyelin exposure, but progression to autophagy engagement was strongly decreased. Together, our results support a two-step model in which EsxA initiates MCV membrane damage, while PDIM amplifies these lesions towards catastrophic rupture, enabling escape to the cytosol and dissemination. Author summary: Pathogenic mycobacteria, including the agent of tuberculosis, infect host cells and reside in a membrane-delimited compartment. During infection, the membrane of this compartment is damaged, activating host repair mechanisms that initially contain the injury and maintain the bacteria inside the compartment. At later stages, the bacteria escape into the host cell cytosol, allowing the progression of the infection, but how this transition from repairable damage to full membrane rupture occurs is not well understood. Using Mycobacterium marinum infection of amoebae and mammalian cells, we found that two previously characterized bacterial factors act in sequence. EsxA, a secreted bacterial protein, triggers initial membrane damage that can be controlled by host repair systems. In contrast, PDIM, a lipid present at the bacterial surface, allows bacteria to overcome these repair mechanisms and progress toward irreversible membrane disruption. Together, our results show how pathogenic mycobacteria use a two-step process to first induce repairable membrane damage and then bypass host repair systems, enabling escape to the cytosol and successful infection.
SN - 1553-7374
SN - 1553-7366
ER -