Bacterial Systems and Synthetic Biology

Our multidisciplinary and multidivisional team of scientists is interested in developing a fundamental understanding of marine bacterial system architecture, regulation, and dynamics for the purpose of re-engineering synthetic constructs for Navy-relevant sensing and decontamination applications. We are addressing these challenges by using a combination of genetic, functional genomic, proteomic, biochemical, physiological, mathematical, and modeling approaches.

Radiation Protection from Melanin

Melanins are high molecular weight pigments, ubiquitous in nature, with a variety of biological functions. Melanized microorganisms (bacteria and fungi) inhabit some remarkably extreme environments and protect against environmental predators, heavy metals toxicity and physical insults such as UV and solar radiation. Most dramatically, melanized fungi colonize and grow towards a high constant radiation field, suggesting a role for melanin in radioprotection and energy transduction.

Mitigation of Warfare Injuries to Neuronal Tissue

Research interests are focused on the understanding of the effects of blast and impact trauma and toxin exposure on human cells, particularly those of the nervous system. Ongoing projects are looking to combine neuronal cell cultures with mechanical sensors in a model of the head and brain in order to determine the mechanisms of how blast waves affect neural cell function. In addition, the work is focused on building a system capable of detecting if protective headgear is able to mitigate blast-induced traumatic brain injury. Other work focuses on determining the effects of low dose exposure of nerve agents to both nervous and liver tissue in order to better understand the long-term risks of this type of exposure.

Dyes are cross-linked to tailless T4 NPs through amine groups and the resulting highly fluorescent dye-T4 can enter eukaryotic cells as shown in the right confocal image. Viral Particles as Scaffolds

Viral scaffolds are protein-based biopolymers and can be tuned for applications' through chemical surface modulation or genetic display. Among these, bacteriophage T4, which contains an icosahedral head encapsulating DNA and a tail, has attracted our attention due to its accessibility and properties.

High resolution XPS from treated and untreated (inset) polystyrene plates. Physico-chemical effects at biointerfaces

The stable integration of a biological recognition element on a transducing substrate surface is the single most important step in the creation of a high-functioning sensor surface. The key factors affecting biotic and abiotic functionalities at the biointerface are both chemical and physical. In collaboration with colleagues in NRL's Plasma Physics Division, we have used electron beam-generated plasmas to modify polymer surfaces with fine control over both chemical functionality and physical features.

Above, circular dichroism showing the ability of sdAb C8 (left) and B4 (right) to refold after heat denaturation. Left shows the ability of both sdAb to bind target after heating cycles. Antibody and Protein Engineering

Our current focus is the development of improved recognition elements for biothreat detection. We work on the development of single domain antibodies (sdAb) derived from llamas as well as conventional antibody fragments (scFv), and a variety of fusion constructs with an eye towards developing improved recognition and signal transduction elements. The sdAb are derived from the unique heavy-chain antibodies found in camelids, and consist of only a variable heavy domain (Figure 1).

Structural Enzymology & Protein Engineering

Using a combination of X-ray crystallography and enzymology we are studying a variety of enzymes relevant to military research. By understanding mechanisms of catalysis we can identify reversible and irreversible mechanism-based inhibitors of bacterial enzymes (potential antimicrobials). Recently, we have examined S-formylglutathione hydrolase (esterase) variants which are activated or inhibited by peroxide and may be useful as biochemical sensors or actuators.