Controlling Enzyme Structure and Activity with Light Illumination

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AbstractProposal Title: Controlling Enzyme Structure and Activity with Light Illumination Proposal Number: CTS-0554115Principal Investigator: C. Ted Lee, Jr.Institution: University of Southern CaliforniaAnalysis (rationale for decision): Enzymes interact with a variety of molecules during the course of activity, resulting in conformation changes to intermediately-folded states that influence nearly all biological processes. Thus, the general form-function relationships of proteins should not be considered static; instead, to fully understand this relationship requires knowledge of how a protein or enzyme unfolds in response to various molecules. To properly investigate this phenomenon requires two complementary approaches: (1) a means to induce protein unfolding in a controlled manner, and (2) a means to study the conformation of unfolded proteins at relatively high resolutions. To achieve this tandem goal, two novel techniques will be pursued in this project, namely the interaction of proteins with photoreversible surfactants, and the use of small-angle neutron scattering (SANS) to determine the structure of partially-folded/unfolded enzymes in response to photoresponsive surfactants. Surfactants unfold proteins by disrupting intramolecular amino acid contacts. In the case of photoresponsive surfactants, the surfactant-amino acid associations can be switched on or off with simple light illumination, resulting in photocontrol of protein conformation. Protein conformation will then be determined with SANS experiments by applying shape-reconstruction methods to optimize the positions of scattering centers (i.e., protein amino acids or individual atoms, depending on the desired resolution) in order to best fit the scattering data. This combined approach will allow full characterization of the photocontrolled native intermediate denatured transitions in enzymes and proteins, providing unique insight into folding pathways. By controlling protein form with light, photocontrol of protein function will also be achieved, allowing enzymatic activity to be switched on and off with light illumination.Photo-controlled enzyme folding requires at a minimum nothing more than a common, commercial black light and, as such, can be easily ported to the classroom to provide an uncomplicated protocol to seamlessly blend research into coursework. This will serve to reconnect the flow of ideas from the laboratory to the curriculum, and will better prepare students to meet the challenges of a technically diverse, modern day workplace. These efforts will be disseminated to the scientific community, particularly the results of Degree Projects, four-year research projects that provide horizontal (over-time) and vertical (cross-course) integration of research and education.