Golden Gate Assembly of Aerobic and Anaerobic Microbial Bioreporters.

Microbial bioreporters provide direct insight into cellular processes by producing a quantifiable signal dictated by reporter gene expression. The core of a bioreporter is a genetic circuit in which a reporter gene (or operon) is fused to promoter and regulatory sequences that govern its expression. In this study, we develop a system for constructing novel Escherichia coli bioreporters based on Golden Gate assembly, a synthetic biology approach for the rapid and seamless fusion of DNA fragments.

Insights Into Arsenite and Arsenate Uptake Pathways Using a Whole Cell Biosensor.

Despite its high toxicity and widespread occurrence in many parts of the world, arsenic (As) concentrations in decentralized water supplies such as domestic wells remain often unquantified. One limitation to effective monitoring is the high cost and lack of portability of current arsenic speciation techniques. Here, we present an arsenic biosensor assay capable of quantifying and determining the bioavailable fraction of arsenic species at environmentally relevant concentrations.

Pseudomonas aeruginosa Biofilm Antibiotic Resistance Gene Expression Requires the RpoS Stationary-Phase Sigma Factor.

Chronic, biofilm-based bacterial infections are exceptionally difficult to eradicate due to the high degree of antibiotic recalcitrance exhibited by cells in biofilm communities. In the opportunistic pathogen , biofilm recalcitrance is multifactorial and arises in part from the preferential expression of resistance genes in biofilms compared to exponential-phase planktonic cells. One such mechanism involves , which we have previously shown to be expressed specifically in biofilms.

Evolution of Cost-Free Resistance under Fluctuating Drug Selection in .

Antibiotic resistance evolves rapidly in response to drug selection, but it can also persist at appreciable levels even after the removal of the antibiotic. This suggests that many resistant strains can both be resistant and have high fitness in the absence of antibiotics. To explore the conditions under which high-fitness, resistant strains evolve and the genetic changes responsible, we used a combination of experimental evolution and whole-genome sequencing to track the acquisition of ciprofloxacin resistance in the opportunistic pathogen under conditions of constant and fluctuating antibiotic delivery patterns.

The biofilm-specific antibiotic resistance gene ndvB is important for expression of ethanol oxidation genes in Pseudomonas aeruginosa biofilms.

Bacteria growing in biofilms are responsible for a large number of persistent infections and are often more resistant to antibiotics than are free-floating bacteria. In a previous study, we identified a Pseudomonas aeruginosa gene, ndvB, which is important for the formation of periplasmic glucans. We established that these glucans function in biofilm-specific antibiotic resistance by sequestering antibiotic molecules away from their cellular targets.

Pseudomonas aeruginosa tssC1 links type VI secretion and biofilm-specific antibiotic resistance.

Biofilm-specific antibiotic resistance is influenced by multiple factors. We demonstrated that Pseudomonas aeruginosa tssC1, a gene implicated in type VI secretion (T6S), is important for resistance of biofilms to a subset of antibiotics. We showed that tssC1 expression is induced in biofilms and confirmed that tssC1 is required for T6S.

Inhibition of TCR signaling by herpes simplex virus.

T lymphocytes are an essential component of the immune response against HSV infection. We previously reported that T cells became functionally impaired or inactivated after contacting HSV-infected fibroblasts. In our current study, we investigate the mechanisms of inactivation.

Dissection of functional domains of the polar localization factor PodJ in Caulobacter crescentus.

The polar organelle development protein, PodJ, is important for proper establishment of polarity in Caulobacter crescentus. podJ null mutants are unable to form holdfast or pili, have reduced swarming motility, and have difficulty ejecting the flagellum during the swarmer to stalked cell transition. In this study, we create a series of truncation mutants to investigate functional domains of PodJ.

The Caulobacter crescentus polar organelle development protein PodJ is differentially localized and is required for polar targeting of the PleC development regulator.

Regulation of polar development and cell division in Caulobacter crescentus relies on the dynamic localization of several proteins to cell poles at specific stages of the cell cycle. The polar organelle development protein, PodJ, is required for the synthesis of the adhesive holdfast and pili. Here we show the cell cycle localization of PodJ and describe a novel role for this protein in controlling the dynamic localization of the developmental regulator PleC.