stress response
Research Article | Molecular Biology and PhysiologyHow the Anaerobic Enteropathogen Clostridioides difficile Tolerates Low O2 TensionsAlthough the gastrointestinal tract is regarded as mainly anoxic, low O2 tension is present in the gut and tends to increase following antibiotic-induced disruption of the host microbiota. Two decreasing O2 gradients are observed, a longitudinal one from the small to the large intestine and a second one from the intestinal epithelium toward the colon lumen. Thus, O2 concentration fluctuations within the...
Research Article | Ecological and Evolutionary ScienceBacterial Evolution in High-Osmolarity EnvironmentsFor bacteria, maintaining higher internal solute concentrations than those present in the environment allows cells to take up water. As a result, survival is challenging in high-osmolarity environments. To investigate how bacteria adapt to high-osmolarity environments, we maintained Escherichia coli in a variety of high-osmolarity solutions for hundreds of generations...
Research Article | Molecular Biology and PhysiologyPolyphosphate Functions In Vivo as an Iron Chelator and Fenton Reaction InhibitorHow do organisms deal with free iron? On the one hand, iron is an essential metal that plays crucial structural and functional roles in many organisms. On the other hand, free iron is extremely toxic, particularly under aerobic conditions, where iron rapidly undergoes the Fenton reaction and produces highly reactive hydroxyl radicals. Our study now demonstrates that we have discovered one of the first physiologically relevant...
Research Article | Host-Microbe BiologyTornadic Shear Stress Induces a Transient, Calcineurin-Dependent Hypervirulent Phenotype in Mucorales MoldsGiven the limited efficacy of current medical treatments in trauma-related necrotizing mucormycosis, there is a dire need to better understand the Mucoralean pathophysiology in order to develop novel strategies to counteract fungal tissue invasion following severe trauma. Here, we describe that tornadic shear stress challenge transiently induces a hypervirulent phenotype in various pathogenic Mucorales species but not in other molds...
Research Article | Molecular Biology and PhysiologyCooperation and Cheating through a Secreted Aminopeptidase in the Pseudomonas aeruginosa RpoS ResponseBacterial stress responses are generally considered protective measures taken by individual cells. Enabled by an experimental evolution approach, we describe a contrasting property, collective nutrient acquisition, in the RpoS-dependent stress response of the opportunistic human pathogen P. aeruginosa. Specifically, we identify the secreted...
Research Article | Molecular Biology and PhysiologyReassessing the Role of the Type II MqsRA Toxin-Antitoxin System in Stress Response and Biofilm Formation: mqsA Is Transcriptionally Uncoupled from mqsRThere is growing controversy regarding the role of chromosomal toxin-antitoxin systems in bacterial physiology. mqsRA is a peculiar toxin-antitoxin system, as the gene encoding the toxin precedes that of the antitoxin. This system was previously shown to play a role in stress response and biofilm formation. In this work, we identified two promoters specifically driving the constitutive expression of the antitoxin, thereby...
Research Article | Host-Microbe BiologyThe Human Cytomegalovirus Nonstructural Glycoprotein UL148 Reorganizes the Endoplasmic ReticulumPerturbations to endoplasmic reticulum (ER) morphology occur during infection with various intracellular pathogens and in certain genetic disorders. We identify that a human cytomegalovirus (HCMV) gene product, UL148, profoundly reorganizes the ER during infection and is sufficient to do so when expressed on its own. Our results reveal that UL148-dependent reorganization of the ER is a prominent feature of HCMV-infected cells. Moreover...
Research Article | Host-Microbe BiologyTranslational Regulation Promotes Oxidative Stress Resistance in the Human Fungal Pathogen Cryptococcus neoformansFungal survival in a mammalian host requires the coordinated expression and downregulation of a large cohort of genes in response to cellular stresses. Initial infection with C. neoformans occurs in the lungs, where it interacts with host macrophages. Surviving macrophage-derived cellular stresses, such as the production of reactive oxygen and nitrogen species, is...
Research Article | Molecular Biology and PhysiologymRNA Degradation Rates Are Coupled to Metabolic Status in Mycobacterium smegmatisThe logistics of tuberculosis therapy are difficult, requiring multiple drugs for many months. Mycobacterium tuberculosis survives in part by entering nongrowing states in which it is metabolically less active and thus less susceptible to antibiotics. Basic knowledge on how M. tuberculosis survives...
Research Article | Molecular Biology and PhysiologyPeptidoglycan Remodeling Enables Escherichia coli To Survive Severe Outer Membrane Assembly DefectIn Gram-negative bacteria, the outer membrane protects the cell against many toxic molecules, and the peptidoglycan layer provides protection against osmotic challenges, allowing bacterial cells to survive in changing environments. Maintaining cell envelope integrity is therefore a question of life or death for a bacterial cell. Here we show that Escherichia coli...