This project will investigate the mechanism of action of cryptochrome blue light photoreceptors in plants. Cryptochromes can sense blue light because the photoreceptor protein is bound to a light-absorbing pigment, flavin (FAD), which undergoes a chemical reaction in response to light. Cryptochromes control how plants grow and develop at many levels, including seed germination, vegetative growth, flowering, and entrainment of the circadian clock. However, very little is known concerning how the light signal is transmitted from the flavin to the protein backbone, and from the protein to the biological target molecules in the cell. The current research project will take a structure/function approach to the question of cryptochrome photoreceptor function by first screening for novel mutations in the cryptochrome protein. Once identified, the cryptochrome genes will be isolated from mutant plants by PCR amplification and the mutations then characterized by direct DNA sequencing. Mutant cryptochrome proteins containing these mutations will then be expressed in a baculovirus expression system at high levels and analyzed by biochemical and structural methods. It will be possible in this way to identify which characteristics of the protein are necessary for normal functioning and thereby better understand the molecular mechanism whereby the light signal is transmitted to its target molecules. Part of this work will be carried out during student summer research in a laboratory at the University of Paris, France, where the required equipment for more detailed structural studies is available.
Broader Impacts: This research project is designed to provide a high quality research experience for undergraduate students. The students will be introduced to an advanced research environment and work directly with scientists. As this introduction is occurring for students at a time when career decisions are being made, it is hoped that the experience will encourage students to pursue graduate studies in science, especially those who may not otherwise have considered research as a career option. A further significant benefit of the current research program is the opportunity provided for working and living in a foreign country during summer study at the University of Paris, with resulting increase in maturity and adaptability of participating students. Funds from this project will also be used to improve the research infrastructure at Penn State Brandywine, providing new equipment and facilities that will be made available to the teaching labs. In this way the research program will improve the content and depth of the lab courses that can be offered to all the students in the degree program. Finally, cryptochrome blue light photoreceptors are found not only in plants, but also in animals such as birds and mammals, and even in humans. There is a lively interest in these receptors in animals since they are involved in the circadian clock in mammals and may be involved in magnetic sensitivity in migratory birds. Since all of the structure/function studies that are performed in this project will equally shed light on how animal type cryptochromes function, the results of this project should be a general understanding of how biological functions in a diverse group of organisms can be controlled by a similar protein, even perhaps adding insights into how birds migrate and on how jet lag works in humans.
