A pore-forming toxin monalysin contributes to infection-induced suppression of defecation in female Drosophila
- 1Research group Genetics of host-microbe interactions, Max Planck Institute for Infection Biology, Berlin, Germany.
- 2Max Planck Unit for the Science of Pathogens, Berlin, Germany.
- 3Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria.
Abstract
Pathogen expulsion from the gut via defecation is an important defence strategy against infection. The microbial factors that can subvert this defence reaction remain poorly understood. While many microbes have been found to increase host intestinal peristalsis, Pseudomonas entomophila infection in Drosophila melanogaster leads to infection-induced defecation blockage, particularly in females. Here, we show that this phenotype is driven by a secreted, thermosensitive protein regulated by the GacS/GacA two-component system. Proteomic comparison of the ΔgacA mutant, which only partially inhibits defecation, and the avirulent Δhfq mutant lacking RNA chaperon Hfq, which still triggers the phenotype, identified pore-forming toxin Monalysin as one of the candidate factors required for inhibiting defecation. Consistent with these findings, the Monalysin-deficient mutant failed to fully suppress defecation and exhibited attenuated virulence and reduced persistence in the gut. Hence, Monalysin besides causing intestinal damage, has a previously unknown role in suppressing defecation and pathogen expulsion. Overall, our study identified a bacterial factor that rapidly reduces defecation frequency, consistent with transient suppression of intestinal transit, thus advancing our understanding of pathogen strategies used to subvert host defences. Author summary: Many intestinal infections affect gut peristalsis, with increased peristalsis helping the host clear harmful microbes through defecation. However, some pathogens may benefit from slowing this process down and persisting in the intestine. We previously found that Pseudomonas entomophila greatly reduces defecation in female fruit flies, but the bacterial factors responsible for this effect remained unknown.
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BibTeX
@article{rubinic2026poreforming,
title = {{A pore-forming toxin monalysin contributes to infection-induced suppression of defecation in female Drosophila}},
author = {Marko Rubinić and Yi Yu and Kathirvel Alagesan and Dagmar Frahm and Igor Iatsenko},
journal = {PLOS Pathogens},
year = {2026},
month = oct,
doi = {10.1371/journal.ppat.1014696},
url = {https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1014696},
note = {CC BY},
}
RIS
TY - JOUR
TI - A pore-forming toxin monalysin contributes to infection-induced suppression of defecation in female Drosophila
AU - Marko Rubinić
AU - Yi Yu
AU - Kathirvel Alagesan
AU - Dagmar Frahm
AU - Igor Iatsenko
PY - 2026
DA - 2026/10/08
JO - PLOS Pathogens
DO - 10.1371/journal.ppat.1014696
UR - https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1014696
AB - Pathogen expulsion from the gut via defecation is an important defence strategy against infection. The microbial factors that can subvert this defence reaction remain poorly understood. While many microbes have been found to increase host intestinal peristalsis, Pseudomonas entomophila infection in Drosophila melanogaster leads to infection-induced defecation blockage, particularly in females. Here, we show that this phenotype is driven by a secreted, thermosensitive protein regulated by the GacS/GacA two-component system. Proteomic comparison of the ΔgacA mutant, which only partially inhibits defecation, and the avirulent Δhfq mutant lacking RNA chaperon Hfq, which still triggers the phenotype, identified pore-forming toxin Monalysin as one of the candidate factors required for inhibiting defecation. Consistent with these findings, the Monalysin-deficient mutant failed to fully suppress defecation and exhibited attenuated virulence and reduced persistence in the gut. Hence, Monalysin besides causing intestinal damage, has a previously unknown role in suppressing defecation and pathogen expulsion. Overall, our study identified a bacterial factor that rapidly reduces defecation frequency, consistent with transient suppression of intestinal transit, thus advancing our understanding of pathogen strategies used to subvert host defences. Author summary: Many intestinal infections affect gut peristalsis, with increased peristalsis helping the host clear harmful microbes through defecation. However, some pathogens may benefit from slowing this process down and persisting in the intestine. We previously found that Pseudomonas entomophila greatly reduces defecation in female fruit flies, but the bacterial factors responsible for this effect remained unknown.
SN - 1553-7374
SN - 1553-7366
ER -