Cryptochrome-based Magnetic Sensors
Abstract
Avian magnetoreception has always impressed upon us a different and superior form of navigation. A key gap in the understanding of protein~based magnetoreception is centered around elucidating and quantifying the conformational changes in cryptochrome that underpin magnetic signal transduction, and their effects on protein~protein interactions. This knowledge will not only provide the first mechanistic link between the quantum spin dynamics of the sensor and the avian nervous system, but also allows us to explore the possibility of engineering magnetic sensors motivated by avian navigation. Furthermore, the ability of a cryptochrome to transduce magnetic stimuli magnetic sensitivity can be tuned by strategic amino acid mutations in the C~terminal domain and in the neighborhood of groups directly involved in photo~induced electron transfer. The cryptochrome hypothesis of avian magnetoreception is focused on uncovering key gaps in the knowledge of the biophysical mechanism, and to exploit these insights to identify the technical challenges involved in the construction of a practical magnetic sensing device. The goal is to decipher the gap from atomic~level information to an understanding how the magnetic signal is propagated and amplified. This fundamental research will inform preliminary work into the design of synthetic bio~organic devices that extract positional and/or directional information from the Earth~s magnetic field. 2. Relevance. Current evidence suggests that migratory songbirds, with a mass of just a few grams, sense both the direction and the intensity of the geomagnetic field, and use this information to perform true navigation. Unlike the other sources of directional and positional information available to animals (sun, stars, odors, landmarks, etc.), the Earth~s magnetic field is omnipresent and, for the most part, not compromised by human activity. If we can determine the fundamental biophysics of this least understood of all sensory mechanisms, the same principles could be used for guiding autonomous or manned vehicles in environments where more established techniques (e.g. GPS) are unavailable, impractical (e.g. under water), compromised, or denied. In the last few years it has become clear that the conductivity and luminescence of certain light~emitting diodes composed entirely of diamagnetic organic molecules can be tuned by weak, externally applied magnetic fields. This extraordinary effect arises because the polaron pairs formed by injecting electrons and holes into these organic semiconductors have essentially identical spin physics to the radical pairs created by photo~induced electron transfer in cryptochromes. Unlike proteins, these organic semiconductors can easily be made electrically addressable and their electrical and magnetic properties can be optimized by molecular design and clever synthetic methods. Unlike Nature, organic chemists are not restricted to amino acids and nucleic acids as the building blocks for sophisticated, bespoke electron donor~acceptor systems. 3. With what PO and ONR Code has this been coordinated? This project has been coordinated with Patrick Bradshaw and Michael Berman, Air Force Office of Scientific Research, who are providing co-funding for this research. 4. Desired outcome. It is becoming clear that migratory animals use a variety of different cues, processing strategies, and behaviors to allow them to return, year after year, over thousands of kilometers, to the same precise location. Globally or regionally stable celestial and geomagnetic information, used for long~distance navigation, probably gives way to learned local gradient maps (based on olfactory and magnetic information) as the animal approaches its destination, which in turn are replaced in the final stage by recognition of specific landmarks and locations. At every point in these journeys, the animal acquires often incomplete data from multiple sources that must be integrated before a decision is made
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Apr 25, 2019
- Source ID
- N629091912045
Entities
People
- Peter Hore
Organizations
- Office of Naval Research
- United States Navy
- University of Oxford