Bai, F. C. | Search bioRxiv

bioRxiv2025

Macrophage-derived reactive oxygen species promote Salmonella aggresome formation contributing to bacterial antibiotic persistence

In this study, we reveal that macrophage-derived reactive oxygen species (ROS) can trigger the rapid formation of Salmonella aggresomes, which substantially contribute to the increased frequency of persisters induced by phagocytosis. Salmonella containing aggresomes exhibited a dormant phenotype characterized by reduced adenosine triphosphate (ATP) levels and decreased metabolic activity. Furthermore, these dormant bacteria showed upregulated expression of Salmonella pathogenicity island 1 (SPI-1)-encoded type III secretion system (T3SS)-related genes, followed by later expression of SPI-2 T3SS-related genes when macrophages ROS production declined. Our results demonstrate that Salmonella containing aggresomes can enter a dormant state to escape antibiotic attack, while crucially maintaining the ability to resuscitate when the stress environment is improved. Research on bacterial aggresomes could potentially provide therapeutic strategies to combat bacterial antibiotic persistence. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=122 SRC="FIGDIR/small/657582v1_ufig1.gif" ALT="Figure 1"> View larger version (55K): org.highwire.dtl.DTLVardef@7e5f1forg.highwire.dtl.DTLVardef@970a39org.highwire.dtl.DTLVardef@204449org.highwire.dtl.DTLVardef@632c47_HPS_FORMAT_FIGEXP M_FIG C_FIG

biophysics↗

bioRxiv2021

Membraneless organelles formed by liquid-liquid phase separation increase bacterial fitness

Liquid-liquid phase separation is emerging as a crucial phenomenon in several fundamental cell processes. A range of eukaryotic systems exhibit liquid condensates. However, their function in bacteria, which in general lack membrane-bound compartments, remains less clear. Here, we used high-resolution optical microscopy to observe single bacterial aggresomes, nanostructured intracellular assemblies of proteins, to undercover their role in cell stress. We find that proteins inside aggresomes are mobile and undergo dynamic turnover, consistent with a liquid state. Our observations are in quantitative agreement with phase-separated liquid droplet formation driven by interacting proteins under thermal equilibrium that nucleate following diffusive collisions in the cytoplasm. We have discovered aggresomes in multiple species of bacteria, and show that these emergent, metastable liquid-structured protein assemblies increase bacterial fitness by enabling cells to tolerate environmental stresses. One Sentence SummaryBacteria use subcellular proteinaceous liquid droplets to survive stress

biophysics↗