A number of natural photoreceptors, in which a chromophore is bound to a protein, utilize light absorption for the regulation of many biological processes.
Recent advances in the understanding of photo-activated proteins have enabled researchers to control biological signaling with unprecedented spatial and temporal resolution. The field of optogenetics exploits these photoreceptors using light and genetic engineering to systematically target and manipulate cellular systems in living organisms controlling physiological processes.
Optogenetic approaches are currently receiving a huge interest as promising tools for neuroscience, and the understanding of the molecular mechanisms of photo-activated proteins is a prerequisite for the functional design of optogenetics tools in the future.
Photoinduced charge transfer reactions are key steps along the receptor photocycle, and their investigation is the focus of this workshop.
Main CT4OPTO Topics:
• Optical properties: A crucial point for the development of optogenetic tools is the tuning of their light sensitivity range. The investigation of the optical properties of photoactive proteins is therefore of paramount importance, as well as the comprehension of the variability, and possible tuning, of light absorption depending on the environmental conditions.
• Excited state dynamics: Photoinduced charge transfer processes occur out of equilibrium, and the significant changes induced by the photoexcitation in both the electronic and nuclear structure of the reactants have to be considered to model the system dynamics. Strategies
and challenges in the theoretical investigation of the excited state dynamics of complex systems will be therefore discussed.
• Proton and electron transfer reactions: Theoretical approaches to treat ET, PT and proton coupled electron transfer (PCET), based both on purely quantum and on QM/MM methods, will be discussed. Experimental techniques to investigate the thermodynamics and kinetics of charge transfer events in photoreceptors will be presented. The investigation of the protein role and response to charge transfer will also be addressed.
• Photoreceptors of current optogenetic interest: The first and most widely used optogenetic tools are light-controlled rhodopsins. More recently, blue-light photoreceptors with flavin chromophores, like LOV (Light Oxygen-Voltage) and BLUF (Blue Light Using Flavin) domains, have been also recruited for optogenetic applications.