Ecotin protects Salmonella Typhimurium against the microbicidal activity of host proteases

Saposnik, L. M.; Coria, L. M.; Bruno, L.; Guaimas, F.; Pandolfi, J. B.; Pol, M.; Urga, M. E.; Sabbione, F.; McClelland, M.; Trevani, A.; Pasquevich, K. A.; Cassataro, J.

doi:10.1101/2024.05.15.594389

bioRxiv · 10.1101/2024.05.15.594389

Ecotin protects Salmonella Typhimurium against the microbicidal activity of host proteases

Saposnik, L. M.·Coria, L. M.·Bruno, L.·Guaimas, F.·Pandolfi, J. B.·Pol, M.·Urga, M. E.·Sabbione, F.·McClelland, M.·Trevani, A.·Pasquevich, K. A.·Cassataro, J.

View original source ↗Export metadata ↓

Abstract

Salmonella enterica serovar Typhimurium causes acute diarrhea upon oral infection in humans. The harsh and proteolytic environment found in the gastrointestinal tract is the first obstacle that these bacteria face after infection. However, the mechanisms that allow Salmonella to survive the hostile conditions of the gut are poorly understood. The ecotin gene is found in an extensive range of known phyla of bacteria and it encodes a protein that has been shown to inhibit serine proteases. Thus, in the present work we studied the role of ecotin of Salmonella Typhimurium in host-pathogen interactions. We found that Salmonella Typhimurium {Delta}ecotin strain exhibited lower inflammation in a murine model of Salmonella induced colitis. The {Delta}ecotin mutant was more susceptible to the action of pancreatin and purified pancreatic elastase. In addition, the lack of ecotin led to impaired adhesion to Caco-2 and HT-29 cell lines, related to the proteolytic activity of brush border enzymes. Besides, {Delta}ecotin showed higher susceptibility to lysosomal proteolytic content and intracellular replication defects in macrophages. In addition, we found Ecotin to have a crucial role in Salmonella against the microbicide action of granules released and neutrophil extracellular traps from human polymorphonuclear leukocytes. Thus, the work presented here highlights the importance of ecotin in Salmonella as countermeasures against the host proteolytic defense system. IMPORTANCEThe gastrointestinal tract is a very complex and harsh environment. Salmonella is a successful food borne pathogen, but little is known about its capacity to survive against the proteolysis of the gut lumen and intracellular proteases. Here, we show that Ecotin, a serine protease inhibitor, plays an important role in protecting Salmonella against proteases present at different sites encountered during oral infection. Our results indicate that Ecotin is an important virulence factor in Salmonella, adding another tool to the wide range of features this pathogen uses during oral infection.

Explore related subjects

microbiology Preprint

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Saposnik, L. M., Coria, L. M., Bruno, L., Guaimas, F., Pandolfi, J. B., Pol, M., Urga, M. E., Sabbione, F., McClelland, M., Trevani, A., Pasquevich, K. A., Cassataro, J.. 2024-05-18. Ecotin protects Salmonella Typhimurium against the microbicidal activity of host proteases. https://doi.org/10.1101/2024.05.15.594389

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Prevalent Integration of both Xenotropic and Ecotropic Murine Leukemia Virus in the Human Genome of Xenografts

Humanized mouse models are widely used in medical research to represent human conditions (1, 2), but their fidelity could be compromised by mouse-originated infections. However, their susceptibility to mouse pathogens are rarely questioned (3). Here we screened 1,619 publicly available genomic sequencing runs from patient-derived xenograft (PDX) models for the integration of murine leukemia virus (MLV), a rodent retrovirus exists in the mouse genome as an endogenous retrovirus (4), within the human genome. We discovered substantial enrichment of human-MLV chimeric DNA in approximately 25% of them. Analyzing the human-MLV junctions, we found about 90% of them bearing the unmistakable hallmarks of retroviral integration, including the canonical MLV boundaries and the distinctive 4-bp target site duplications (5, 6). It was also assumed that mouse strains without the highly infectious Bxv1 provirus are safe from MLV contamination in xenografts (7, 8). However, we found many PDX models derived from Bxv1- strains, including the widely used NSG strain, are also contaminated by the supposedly rodent-specific ecotropic MLV (E-MLV). We further confirmed a complete E-MLV integrated into the human genome by both HiFi and sanger sequencing. Our discovery raises concerns that mouse-to-human retroviral transmission and integration is more common and less restrictive than previously appreciated. They support examination of MLV integration as a feature of humanized mouse models with implications on the fidelity of these models in recapitulating human cells and tissues. Our discovery also has underscored the importance of comprehensively inactivation of porcine endogenous retroviruses for the clinical application of xenotransplatation (9, 10).

microbiology↗

bioRxiv2026

Necroptosis is a targetable driver of severe coronavirus pathogenesis

Human-pathogenic coronaviruses differ dramatically in pathogenicity but the underlying mechanisms are incompletely understood. Here, we demonstrate that highly pathogenic coronaviruses trigger necroptosis in the infected cells and lung tissues, whereas necroptosis is not detected in cells infected by seasonal coronavirus. Mechanistically, highly pathogenic coronaviruses produce Z-RNA, activate ZBP1 and initiates necroptotic cell death signaling, triggering necroinflammation and lung injury. In contrast, seasonal coronaviruses produce little to no Z-RNA, and do not activate necroptosis. Importantly, small-molecule inhibition of necroptosis attenuates inflammatory cytokine expression and markedly ameliorates lung damage in mice infected with all three highly pathogenic coronaviruses, independent of virus clearance. Overall, our study identifies necroptosis as a dominant mediator of coronavirus pathogenesis, and positions necroptosis blockade as a new therapeutic target against severe coronavirus diseases.

microbiology↗

bioRxiv2026

POM121 regulates lentiviral nuclear import in a capsid-host factor-dependent manner

Lentiviruses such as human immunodeficiency virus 1 (HIV-1) access the nuclear lumen through the nuclear pore complex (NPC), a process coordinated by the interactions between the viral capsid and nucleoporins (NUPs). Here, using unbiased proteomic screens, we identified several capsid-associated NUPs, including POM121. Depletion of POM121 impaired HIV-1 infection in multiple cell lines and in primary CD4+ T cells, whereas equine infectious anaemia virus (EIAV) infection was enhanced, indicating that POM121 effect is virus-specific. A cytoplasmic carboxy-terminal fragment of POM121, containing its FG-rich region inhibited HIV-1 and a broader range of lentiviruses. Analysis of HIV-1 capsid mutants showed that physical interaction with POM121 does not predict functional dependence, as capsids retaining POM121 binding remained insensitive to its depletion. Strikingly, loss of cyclophilin A (CypA) completely abolished HIV-1 dependence on POM121, whereas depletion of CPSF6 produced only partial rescue, demonstrating that POM121 sensitivity is dictated by the broader network of capsid-host interactions. Finally, POM121 depletion impaired HIV-1 nuclear accumulation and selectively disrupted the nuclear import of other viral and cellular cargo. Together, these findings identify POM121 as a selective regulator of lentiviral nuclear entry whose functional contribution is determined by capsid and host-factor context.

microbiology↗