PHOTOCOUPLED TIME-RESOLVED SMALL ANGLE X-RAY SCATTERING APPLIED TO A BLUE LIGHT SENSING PROTEIN
Lamb, Jessica Scherrer
Many molecules relevant to life respond to changes in their environment by large changes in shape, by which the carry out an important function. Under- standing of these systems can be gained through study with methods which can map out the global conformational changes the molecule undergoes over time. Time-resolved small angle x-ray scattering is one such method. We have engineered a photocoupled flow cell which allows us to initiate changes in pro- teins via light excitation and measure them with a capillary focused x-ray beam. We have also considered the analysis of time-resolved SAXS data, which can be acquired using such a system, with recently popular reconstruction methods. These techniques have been applied to the study of VVD, a blue light photosen- sor in the PAS-LOV family of proteins. This large family of proteins is found in all kingdoms of life and is important for transducing environmental signals into biological actions. These studies provide insight into rapid dimerization of the protein upon photoexcitation. Such information is important to understanding not only VVD signaling but also the mechanisms by which other PAS-LOV proteins operate.
small angle X-ray scattering; PAS-LOV protein; time-resolved methods; photoexcitation