Browsing by Subject "Light"
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Item [Southwestern News](1999-05-25) Steeves, Susan A.Item Structural Basis for Signal Transduction in LOV Blue Light Photoreceptors(2011-08-10) Nash, Abigail I.; Gardner, Kevin H.This research focused on studying the mechanisms of signal transduction within Light-Oxygen-Voltage domains, a subset of the PAS domain family. The first of two projects addressed intradomain signaling from the hydrophobic core to the domain surface. In this study, we addressed the role of a specific conserved residue in transmitting activating signal from the domain core to surface structural elements. Through biophysical and biochemical studies of LOV proteins containing point mutations at key residues, we determined that structural strain placed on the domain following light-induced covalent adduct formation regulates both structural based signal transduction as well as dark state recovery kinetics. In the second project, I characterized a novel LOV containing protein comprised of an N-terminal LOV domain and a C-terminal DNA binding helix-turn-helix (HTH) domain. Following initial characterization of this protein, I was able to determine how light-induced covalent adduct formation in the N-terminus leads to interdomain separation through release of inhibitory contacts with the HTH domain, allowing for DNA binding. Comparisons of this protein with other known HTH proteins highlight the conserved signal transduction pathways of both the LOV domain and the HTH domain.Item Using Light-Activated EFG to Control Cell Behavior with Automated Instrumentation(2008-05-13) Miller, Danielle Suzanne; Luebke, Kevin J.A key interest in cell biology is the ability to control cell behavior, particularly for creating functional assemblies of cells to restore, maintain or enhance tissue and organ function. Success in controlling cell behavior must include techniques that provide signals which influence the organization, growth and activities of cells. Growth factors are naturally occurring proteins that act as external chemical signals and which play a key role in regulation and control of a variety of cellular processes, such as differentiation, proliferation and migration. One of the challenges in controlling these processes using growth factors is the ability to spatially direct their timed release to the cellular environment. Another challenge then becomes the continued ability to influence these processes with the dynamic flexibility to meet the changing cellular demands during tissue development. We have developed a technology that uses light-activated epidermal growth factor (EGF) to influence cell behavior. We used peptide synthesis to incorporate a photolabile caging group on a critical residue. The caged-growth factor was inactive until converted with light, which enabled the management of its effects with the precision with which light could be directed. Since the factor was a soluble, diffusible species, it was not limited to a static pattern or substrate. Thus, dynamic control over its mitogenic and chemotactic effects on cell behavior was achieved. To utilize the light-activated EGF we developed a device for its delivery and activation. The system was a fully automated machine capable of maintaining the strict requirements of cell culture, integrated with components that achieved interchangeable, high resolution patterns, along with an optical system for photo-activating caged growth factors. The instrument was designed, characterized and then used to investigate the effect of light-activated EGF on cell patterning and mobility. Using this device, spatially resolved fibroblast cell patterning and migration were achieved.Item [UT Southwestern Medical Center News](2008-06-16) Siegfried, Amanda