Biology subjects

Liebler-Tenorio, E.

Publications and source records attributed to Liebler-Tenorio, E..

3 recordsLinked to original sources

bioRxiv2026

TFEB and MCOLN1 are important for Coxiella burnetii egress via lysosomal exocytosis

Coxiella burnetii is a Gram-negative, obligate intracellular pathogen and the causative agent of the zoonotic disease Q fever. Resident alveolar macrophages are the first target cells, but C. burnetii spreads to other cell types. While we have information about C. burnetii uptake and the establishment of the replication-competent phagolysosomal-like C. burnetii-containing vacuole (CCV), it is not well studied how C. burnetii exits its host cell. Here, we show that an infection with C. burnetii also triggers the activation of TFEB, a master regulator of autophagy and lysosomal development. The activation occurs in a time-dependent manner and depends on the size of the CCV. Importantly, TFEB activation during C. burnetii infection depend on MCOLN1, which channels Ca2+ across the lysosomal membrane into the cytosol. Knock-down of MCOLN1 resulted in reduced TFEB activation and smaller CCVs, while MCOLN1 activation boosted bacterial egress. Indeed, peripheral CCVs are positive for LAMP1/2 and release bacteria, without inducing host cell death. Importantly, LAMP1/2 and C. burnetii were stainable in non-permeabilized cells at sites of bacterial release, demonstrating fusion of the lysosome with the plasma membrane. Importantly, while replication of C. burnetii is not inhibited in cells lacking LAMP1/2, egress is impaired. Taken together, our data indicates that with increasing CCV size, TFEB is activated by the release of Ca2+ from lysosomes via the MCOLN1 channel, which in turn enables further CCV development and damage of the CCV membrane. This triggers lysosomal exocytosis and egress of C. burnetii without cell death induction.

microbiology↗

bioRxiv2025

Coxiella burnetii establishes a small cell variant (SCV)-like persistent form to survive adverse intracellular conditions

Coxiella burnetii is an obligate intracellular zoonotic bacterium that causes Q fever. Infections can be either acute or chronic. Of note, chronic Q fever develops months or years after primary infection without clinical symptoms, suggesting bacterial persistence. Yet, information about the induction, regulation and/or location of C. burnetii persistence is rare. We have shown that during infection of primary macrophages, hypoxia-induced citrate limitation results in inhibition of C. burnetii replication without affecting viability. Here, primary murine macrophages were infected with C. burnetii under normoxic (21% O2) and hypoxic (0.5% O2) conditions to clarify how C. burnetii survives this environmental stress condition. Our data suggests that under hypoxic conditions C. burnetii does not undergo stringent response, but instead enters a SCV-like form, which is smaller in size and possesses condensed chromatin material and a thicker cell wall. These changes have functional consequences, as the SCV-like persistent form of C. burnetii is more infectious, more tolerant to antibiotics and less sensitive to clearance by IFN{gamma} activated macrophages. Hence, the development of the SCV-like persistent form of C. burnetii prevents elimination of the pathogen, which in turn allows the pathogen to thrive once the conditions again change in its favor.

microbiology↗

bioRxiv2022

Dissecting the invasion of Galleria mellonella by Yersinia enterocolitica reveals metabolic adaptations and a role of a phage lysis cassette in insect killing

The human pathogen Yersinia enterocolitica strain W22703 is characterized by its toxicity towards invertebrates that requires the insecticidal toxin complex (Tc) proteins encoded by the pathogenicity island Tc-PAIYe. Molecular and pathophysiological details of insect larvae infection and killing by this pathogen, however, have not been dissected. Here, we applied oral infection of Galleria mellonella (Greater wax moth) larvae to study the colonisation, proliferation, tissue invasion, and killing activity of W22703. We demonstrated that this strain is strongly toxic towards the larvae, in which they proliferate by more than three orders of magnitude within six days post infection. Deletion mutants of genes tcaA and tccC were atoxic for the insect. W22703 {Delta}tccC, in contrast to W22703 {Delta}tcaA, initially proliferated before being eliminated from the host, thus confirming TcaA and TccC as membrane-binding Tc subunit and ADP-ribosylating enzyme, respectively. Time course experiments revealed a Tc-dependent infection process starting with midgut colonisation that is followed by invasion of the hemolymph where the pathogen elicits morphological changes of hemocytes and strongly proliferates. The in vivo transcriptome of strain W22703 shows that the pathogen undergoes a drastic reprogramming of central cell functions and gains access to numerous carbohydrate and amino acid resources within the insect. Strikingly, a mutant lacking a phage-related holin/endolysin (HE) cassette, which is located within Tc-PAIYe, resembled the phenotypes of W22703 {Delta}tcaA, suggesting that this dual lysis cassette is an example for a phage-related function that has been adapted for the release of a bacterial toxin.

microbiology↗