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Research

The general goal of our research program is to probe the inner-workings of Nature's molecular and cellular machinery through functional measurement. Building from a molecular perspective we and collaborators employ a measure-make-model approach including single molecule biophysics methods of optical tweezers, single molecule fluorescence spectroscopy, functional mutations and simulations. Our long-range goals include laying the foundation for forward engineering with physical biological parts and hybrid systems in addition to identifying strategies for fighting disease.

Our tools combine optical tweezers and single molecule fluorescence, force-fluorescence microscopy, to measure the molecular underpinnings of molecular and cellular machinery. These two techniques provide complementary information about the system of interest. Single molecule fluorescence can report on the conformational state of a biomolecule, while optical tweezers allow for the mechanical manipulation of proteins with position and force resolutions on the order of nm and pN, respectively. Using state of the art equipment developed in our lab, we are combining force and fluorescence spectroscopic capabilities to tackle novel biological problems at the molecular and cellular levels.

Three current projects are featured below:

Biological motors: We have a variety of projects surrounding the study of biological motors. In particular, we are probing the machinery of the ClpXP motor protease, which destroys proteins tagged for removal from cells. ClpXP is a member of the AAA+ class of mechanoenzymes, cellular engines that power many processes, such as protein degradation, DNA replication, membrane fusion and motility along microtubules. ClpXP performs many tasks including recognition, unfolding, translocation, denaturation and degradation of proteins. We employ both a single molecule fluorescence and mechanical assay to probe the machinery of ClpXP.

Amyloid based structure and function: Amyloid fibers are central to both disease and natural biological processes. Amyloid fibers have potential as nanomaterials and are agents for biofilm formation. Our lab studies the physical basis for structure, function, and nanomaterial applications of amyloid fibers. We are leveraging our newly developed single molecule force-fluorescence assay for probing single amyloid tethers. Among other fiber-based studies, we are probing molecular and network interactions underlying actin machinery.

Cell signaling and immunology: Our body's natural defense system employs antigen recognition and signaling through specialized cells known as lymphocytes. Cell antigen interactions, that mimic natural events such as encountering an antigen coated bead, are actively created with our automated optical traps to investigate the signaling machinery of the antigen receptor. Downstream cellular response is probed through both fluorescence imaging and physical measurement.

A number of prior studies are featured below:

Force-Fluorescence Instrumentation
Force Generation Mechanism of Kinesin
Studies of Actin Machinery
Bacteriophage Tethers
Active Assembly over Silicon Wafers