Date of Award
5-2025
Document Type
Essay
Department
Chemistry and Biochemistry
First Advisor
Dr. Jesse Kleingardner
Abstract
Microbial rhodopsins are a family of photochemically reactive proteins found in prokaryotes and lower eukaryotes in a variety of habitats. Like the rhodopsins in animal vision, microbial rhodopsins have seven transmembrane helices that form a pocket containing the chromophore retinal, which is bound to a Schiff base in the 7th helix. The biological roles of microbial rhodopsins are diverse, but most act either as photoenergy transducers or photosensory receptors. Because they use precise light exposures to regulate transmembrane ion currents, research is being done to apply microbial rhodopsins to optogenetics. This is a rapidly growing field that uses light to control cell membrane potentials, particularly in neurons. As it allows for precise control over neuronal activity, optogenetics is reshaping the study of neural circuits. For example, microbial rhodopsins can be used optogenetically to hyperpolarize the neural plasma membrane, thus increasing the required electrical threshold to trigger action potentials. Alternatively, they can be used to suppress neurotransmitter release or to change the internal pH of cell membranes in a non-invasive way. These strategies are currently being refined to investigate specific mechanisms in neural behaviors and pathologies. Only a select array of microbial rhodopsins have been harnessed to optogenetic research, with channelrhodopsins being the original and most widely used, and archaerhodopsins being a close second. The characteristics of a specific rhodopsin class have a significant effect on its potential as an optogenetic tool. For example, whether it is fast- or slow-channel closing, blue- or red-shifted, or a transporter of cations or anions all determine how it can be used in the research lab, or eventually the clinic. The available types of microbial rhodopsins limits the expansion of rhodopsin- based optogenetic research. Thus, much research has been done recently to identify additional types of microbial rhodopsins that can be used to build the arsenal of optogenetic techniques. This article will review the structure and functions of the main types of microbial rhodopsins in optogenetics.
Recommended Citation
Kersten, Elise, "Microbial Rhodopsins in Optogenetics" (2025). Chemistry Student Scholarship. 2.
https://mosaic.messiah.edu/chem_st/2
