CRISPR-Cas in Pseudomonas aeruginosa provides transient population-level immunity against high phage exposures.

The prokaryotic adaptive immune system, CRISPR-Cas (clustered regularly interspaced short palindromic repeats; CRISPR-associated), requires the acquisition of spacer sequences that target invading mobile genetic elements such as phages. Previous work has identified ecological variables that drive the evolution of CRISPR-based immunity of the model organism Pseudomonas aeruginosa PA14 against its phage DMS3vir, resulting in rapid phage extinction. However, it is unclear if and how stable such acquired immunity is within bacterial populations, and how this depends on the environment.

Visualizing the subcellular localization of RHOB-GTP and GTPase-Effector complexes using a split-GFP/nanobody labelling assay.

Small GTPases are highly regulated proteins that control essential signaling pathways through the activity of their effector proteins. Among the RHOA subfamily, RHOB regulates peculiar functions that could be associated with the control of the endocytic trafficking of signaling proteins. Here, we used an optimized assay based on tripartite split-GFP complementation to localize GTPase-effector complexes with high-resolution.

Ecology and evolution of phages encoding anti-CRISPR proteins.

CRISPR-Cas are prokaryotic defence systems that provide protection against invasion by mobile genetic elements (MGE), including bacteriophages. MGE can overcome CRISPR-Cas defences by encoding anti-CRISPR (Acr) proteins. These proteins are produced in the early stages of the infection and inhibit the CRISPR-Cas machinery to allow phage replication.

Antibiotics that affect translation can antagonize phage infectivity by interfering with the deployment of counter-defenses.

It is becoming increasingly clear that antibiotics can both positively and negatively impact the infectivity of bacteriophages (phage), but the underlying mechanisms often remain unclear. Here we demonstrate that antibiotics that target the protein translation machinery can fundamentally alter the outcome of bacteria-phage interactions by interfering with the production of phage-encoded counter-defense proteins. Specifically, using Pseudomonas aeruginosa PA14 and phage DMS3vir as a model, we show that bacteria with Clustered Regularly Interspaced Short Palindromic Repeat, CRISPR associated (CRISPR-Cas) immune systems have elevated levels of immunity against phage that encode anti-CRISPR (acr) genes when translation inhibitors are present in the environment.

Interactions between bacterial and phage communities in natural environments.

We commonly acknowledge that bacterial viruses (phages) shape the composition and evolution of bacterial communities in nature and therefore have important roles in ecosystem functioning. This view stems from studies in the 1990s to the first decade of the twenty-first century that revealed high viral abundance, high viral diversity and virus-induced microbial death in aquatic ecosystems as well as an association between collapses in bacterial density and peaks in phage abundance. The recent surge in metagenomic analyses has provided deeper insight into the abundance, genomic diversity and spatio-temporal dynamics of phages in a wide variety of ecosystems, ranging from deep oceans to soil and the mammalian digestive tract.

Functional Study of Cytolethal Distending Toxin Subunit B.

The Cytolethal Distending Toxin (CDT) is produced by many Gram-negative pathogenic bacteria responsible for major foodborne diseases worldwide. CDT induces DNA damage and cell cycle arrest in host-cells, eventually leading to senescence or apoptosis. According to structural and sequence comparison, the catalytic subunit CdtB is suggested to possess both nuclease and phosphatase activities, carried by a single catalytic site.

Cytolethal Distending Toxin Subunit B: A Review of Structure-Function Relationship.

The Cytolethal Distending Toxin (CDT) is a bacterial virulence factor produced by several Gram-negative pathogenic bacteria. These bacteria, found in distinct niches, cause diverse infectious diseases and produce CDTs differing in sequence and structure. CDTs have been involved in the pathogenicity of the associated bacteria by promoting persistent infection.

Cell transfection of purified cytolethal distending toxin B subunits allows comparing their nuclease activity while plasmid degradation assay does not.

The Cytolethal Distending Toxin (CDT) is produced by many pathogenic bacteria. CDT is known to induce genomic DNA damage to host eukaryotic cells through its catalytic subunit, CdtB. CdtB is structurally homologous to DNase I and has a nuclease activity, dependent on several key residues.

promotes colorectal tumorigenesis through the action of cytolethal distending toxin.

Objective: produces a genotoxin, cytolethal distending toxin (CDT), which has DNAse activity and causes DNA double-strand breaks. Although infection has been shown to promote intestinal inflammation, the impact of this bacterium on carcinogenesis has never been examined.

Design: Germ-free (GF) mice, fed with 1% dextran sulfate sodium, were used to test tumorigenesis potential of CDT-producing .