Quorum sensing inhibits interference competition among bacterial symbionts within a host.

The symbioses that animals form with bacteria play important roles in health and disease, but the molecular details underlying how bacterial symbionts initially assemble within a host remain unclear. The bioluminescent bacterium Vibrio fischeri establishes a light-emitting symbiosis with the Hawaiian bobtail squid Euprymna scolopes by colonizing specific epithelium-lined crypt spaces within a symbiotic organ called the light organ. Competition for these colonization sites occurs between different strains of V.

The QseB response regulator imparts tolerance to positively charged antibiotics by controlling metabolism and minor changes to LPS.

The modification of lipopolysaccharide (LPS) in and spp. is primarily controlled by the two-component system PmrAB. LPS modification allows bacteria to avoid killing by positively charged antibiotics like polymyxin B (PMB).

Two enhancer binding proteins activate σ-dependent transcription of a quorum regulatory RNA in a bacterial symbiont.

To colonize a host, bacteria depend on an ensemble of signaling systems to convert information about the various environments encountered within the host into specific cellular activities. How these signaling systems coordinate transitions between cellular states in vivo remains poorly understood. To address this knowledge gap, we investigated how the bacterial symbiont initially colonizes the light organ of the Hawaiian bobtail squid .

The type-VI secretion system of the beneficial symbiont .

The mutualistic symbiosis between the Hawaiian bobtail squid and the marine bacterium is a powerful experimental system for determining how intercellular interactions impact animal-bacterial associations. In nature, this symbiosis features multiple strains of within each adult animal, which indicates that different strains initially colonize each squid. Various studies have demonstrated that certain strains of possess a type-VI secretion system (T6SS), which can inhibit other strains from establishing symbiosis within the same host habitat.

The QseB response regulator imparts tolerance to positively charged antibiotics by controlling metabolism and minor changes to LPS.

Unlabelled: The modification of lipopolysaccharide (LPS) in and . is primarily controlled by the two-component system PmrAB. LPS modification allows bacteria to avoid killing by positively charged antibiotics like polymyxin B.

The Bacterial Enhancer Binding Protein VasH Promotes Expression of a Type VI Secretion System in Vibrio fischeri during Symbiosis.

is a bacterial symbiont that colonizes the light organ of the Hawaiian bobtail squid, Certain strains of express a type VI secretion system (T6SS), which delivers effectors into neighboring cells that result in their death. Strains that are susceptible to the T6SS fail to establish symbiosis with a T6SS-positive strain within the same location of the squid light organ, which is a phenomenon termed strain incompatibility. This study investigates the regulation of the T6SS in strain FQ-A001.

Incompatibility of Vibrio fischeri Strains during Symbiosis Establishment Depends on Two Functionally Redundant Genes.

Bacteria that have the capacity to fill the same niche will compete with one another for the space and resources available within an ecosystem. Such competition is heightened among different strains of the same bacterial species. Nevertheless, different strains often inhabit the same host.

Bacterial symbionts use a type VI secretion system to eliminate competitors in their natural host.

Intraspecific competition describes the negative interaction that occurs when different populations of the same species attempt to fill the same niche. Such competition is predicted to occur among host-associated bacteria but has been challenging to study in natural biological systems. Although many bioluminescent strains exist in seawater, only a few strains are found in the light-organ crypts of an individual wild-caught squid, suggesting a possible role for intraspecific competition during early colonization.

Characterization of blue light irradiation effects on pathogenic and nonpathogenic Escherichia coli.

Blue light irradiation (BLI) is an FDA-approved method for treating certain types of infections, like acne, and is becoming increasingly attractive as an antimicrobial strategy as the prevalence of antibiotic-resistant "superbugs" rises. However, no study has delineated the effectiveness of BLI throughout different bacterial growth phases, especially in more BLI-tolerant organisms such as Escherichia coli. While the vast majority of E.

Signaling by two-component system noncognate partners promotes intrinsic tolerance to polymyxin B in uropathogenic Escherichia coli.

Bacteria use two-component systems (TCSs) to react appropriately to environmental stimuli. Typical TCSs comprise a sensor histidine kinase that acts as a receptor coupled to a partner response regulator that coordinates changes in bacterial behavior, often through its activity as a transcriptional regulator. TCS interactions are typically confined to cognate pairs of histidine kinases and response regulators.

Purine Biosynthesis Metabolically Constrains Intracellular Survival of Uropathogenic Escherichia coli.

The ability to de novo synthesize purines has been associated with the intracellular survival of multiple bacterial pathogens. Uropathogenic Escherichia coli (UPEC), the predominant cause of urinary tract infections, undergoes a transient intracellular lifestyle during which bacteria clonally expand into multicellular bacterial communities within the cytoplasm of bladder epithelial cells. Here, we characterized the contribution of the conserved de novo purine biosynthesis-associated locus cvpA-purF to UPEC pathogenesis.

Strong cross-system interactions drive the activation of the QseB response regulator in the absence of its cognate sensor.

Bacterial two-component systems (TCSs) mediate specific responses to distinct conditions and/or stresses. TCS interactions are highly specific between cognate partners to avoid unintended cross-talk. Although cross-talk between a sensor kinase and a noncognate response regulator has been previously demonstrated, the majority of reported interactions have not been robust.