Structural Basis for Signal Transduction in LOV Blue Light Photoreceptors

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.