Stress-dependent activation of the Listeria monocytogenes virulence program ensures bacterial resilience during infection
ABSTRACT Listeria monocytogenes (Lm) is a Gram-positive, facultative intracellular pathogen that uses both a housekeeping (P1) and stress-activated (Sigma B-dependent) promoter (P2) to express the master virulence regulator PrfA. The Sigma B regulon contains over 300 genes known to respond to differ...
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American Society for Microbiology
2025-06-01
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| Series: | mBio |
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| Online Access: | https://journals.asm.org/doi/10.1128/mbio.00719-25 |
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| author | Mariya Lobanovska Ying Feng Jonathan Zhang Allison H. Williams Daniel A. Portnoy |
| author_facet | Mariya Lobanovska Ying Feng Jonathan Zhang Allison H. Williams Daniel A. Portnoy |
| author_sort | Mariya Lobanovska |
| collection | DOAJ |
| description | ABSTRACT Listeria monocytogenes (Lm) is a Gram-positive, facultative intracellular pathogen that uses both a housekeeping (P1) and stress-activated (Sigma B-dependent) promoter (P2) to express the master virulence regulator PrfA. The Sigma B regulon contains over 300 genes known to respond to different stressors. However, the role of Sigma B in the regulation of prfA during the infection remains uncertain. To define pathways that lead to Sigma B-dependent prfA activation, we performed a genetic screen in L2 fibroblasts using ΔP1 Lm that only has the Sigma B-dependent promoter directly upstream of prfA. The screen identified transposon insertions in a large bacterial sensory organelle known as the stressosome. The absence of functional stressosome components resulted in heterogeneity within bacterial populations, with some bacteria behaving like wild type, while other members of the population exhibited defects in either vacuolar escape and/or cell-to-cell spread. We show that the heterogeneity of the stressosome mutants cannot be rescued by constitutive activation of PrfA. These data defined the importance of the stressosome in controlling bacterial homogeneity and characterized the function of the stressosome in robust virulence activation during infection. ΔP1 Lm model provides new opportunities to identify host-specific signals necessary for stressosome-dependent signaling during Listeria pathogenesis.IMPORTANCEMicrobial pathogens must adapt to varying levels of stress to survive. This study uncovered a link between stress sensing and activation of the virulence program in a facultative intracellular pathogen, Listeria monocytogenes. We show that host-imposed stress is sensed by the signaling machinery known as the stressosome to ensure robust and resilient virulence responses in vivo. Stressosome-dependent activation of the master virulence regulator PrfA was necessary to maintain L. monocytogenes homogeneity within the bacteria population during the transition between early and late stages of intracellular infection. This work also provides a model to further characterize how specific stress stimuli affect bacterial survival within the host, which is critical for our understanding of bacterial pathogenesis. |
| format | Article |
| id | doaj-art-0232b6eb9d104845bae904da0d52d7eb |
| institution | OA Journals |
| issn | 2150-7511 |
| language | English |
| publishDate | 2025-06-01 |
| publisher | American Society for Microbiology |
| record_format | Article |
| series | mBio |
| spelling | doaj-art-0232b6eb9d104845bae904da0d52d7eb2025-08-20T02:32:53ZengAmerican Society for MicrobiologymBio2150-75112025-06-0116610.1128/mbio.00719-25Stress-dependent activation of the Listeria monocytogenes virulence program ensures bacterial resilience during infectionMariya Lobanovska0Ying Feng1Jonathan Zhang2Allison H. Williams3Daniel A. Portnoy4Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, USADepartment of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, USADepartment of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, USADepartment of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, California, USADepartment of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, USAABSTRACT Listeria monocytogenes (Lm) is a Gram-positive, facultative intracellular pathogen that uses both a housekeeping (P1) and stress-activated (Sigma B-dependent) promoter (P2) to express the master virulence regulator PrfA. The Sigma B regulon contains over 300 genes known to respond to different stressors. However, the role of Sigma B in the regulation of prfA during the infection remains uncertain. To define pathways that lead to Sigma B-dependent prfA activation, we performed a genetic screen in L2 fibroblasts using ΔP1 Lm that only has the Sigma B-dependent promoter directly upstream of prfA. The screen identified transposon insertions in a large bacterial sensory organelle known as the stressosome. The absence of functional stressosome components resulted in heterogeneity within bacterial populations, with some bacteria behaving like wild type, while other members of the population exhibited defects in either vacuolar escape and/or cell-to-cell spread. We show that the heterogeneity of the stressosome mutants cannot be rescued by constitutive activation of PrfA. These data defined the importance of the stressosome in controlling bacterial homogeneity and characterized the function of the stressosome in robust virulence activation during infection. ΔP1 Lm model provides new opportunities to identify host-specific signals necessary for stressosome-dependent signaling during Listeria pathogenesis.IMPORTANCEMicrobial pathogens must adapt to varying levels of stress to survive. This study uncovered a link between stress sensing and activation of the virulence program in a facultative intracellular pathogen, Listeria monocytogenes. We show that host-imposed stress is sensed by the signaling machinery known as the stressosome to ensure robust and resilient virulence responses in vivo. Stressosome-dependent activation of the master virulence regulator PrfA was necessary to maintain L. monocytogenes homogeneity within the bacteria population during the transition between early and late stages of intracellular infection. This work also provides a model to further characterize how specific stress stimuli affect bacterial survival within the host, which is critical for our understanding of bacterial pathogenesis.https://journals.asm.org/doi/10.1128/mbio.00719-25intracellular bacteriapathogenesisstress adaptationsigma factorsvirulence regulationmacrophages |
| spellingShingle | Mariya Lobanovska Ying Feng Jonathan Zhang Allison H. Williams Daniel A. Portnoy Stress-dependent activation of the Listeria monocytogenes virulence program ensures bacterial resilience during infection mBio intracellular bacteria pathogenesis stress adaptation sigma factors virulence regulation macrophages |
| title | Stress-dependent activation of the Listeria monocytogenes virulence program ensures bacterial resilience during infection |
| title_full | Stress-dependent activation of the Listeria monocytogenes virulence program ensures bacterial resilience during infection |
| title_fullStr | Stress-dependent activation of the Listeria monocytogenes virulence program ensures bacterial resilience during infection |
| title_full_unstemmed | Stress-dependent activation of the Listeria monocytogenes virulence program ensures bacterial resilience during infection |
| title_short | Stress-dependent activation of the Listeria monocytogenes virulence program ensures bacterial resilience during infection |
| title_sort | stress dependent activation of the listeria monocytogenes virulence program ensures bacterial resilience during infection |
| topic | intracellular bacteria pathogenesis stress adaptation sigma factors virulence regulation macrophages |
| url | https://journals.asm.org/doi/10.1128/mbio.00719-25 |
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