Determination of the Role of Tyrosine-319 on the Efficiency of Photoinduced Radical Pairs in Avian Cryptochrome Photoreceptor Proteins Related to Magnetoreception
Author
Signorelli, Rachel Lee
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Abstract
Cryptochromes (CRYs) are flavin-containing blue light photoreceptors which are involved in circadian rhythms and magnetoreception. CRYs are structurally related to DNA photolyases. While photolyases use light-driven FAD oxidation to catalyze light-dependent DNA repair, CRYs
use FAD photoreduction to drive the conformational change of a C-terminal tail (CTT) linked to cell signaling. CRYs were first identified in Arabidopsis thaliana and have since been identified in prokaryotes, archaea, and eukaryotes. An emerging class of CRY proteins, particularly CRY4, is thought to play a key role in light-dependent magnetoreception for migratory birds (as well as fish and reptiles); it is considered to act as a biological magnetic compass. CRYs exist in an inactive ground state with an oxidized flavin, and the absorption of blue UV light promotes the transfer of an electron (ET) from a tryptophan residue to reduce the excited state FAD* molecule. The resulting radical ‘hops’ or propagates along a chain of four conserved and functionally important tryptophan (Trp) residues. The resulting electron spins on FAD• and Trp• are coherent and considered ‘entangled’ – a quantum mechanical property. This quantum effect is thought to be related to the ability for birds to ‘sense’ the Earth’s magnetic field. A recent crystal structure of a C. livia (pigeon) CRY4 reveals a redox-active tyrosine residue in close proximity to the terminal Trp tetrad. The role of this semi-conserved tyrosine, Y319, in ET and hence magnetoreception, is unknown. In this thesis, the recombinant expression of the wild-type ClCRY4 in bacterial cultures was optimized, and site-directed mutagenesis was performed to Y319. Preliminary spectroscopic studies implicate a potential role for Y319 in ET. These structure-function studies are expected to shed light onto the fundamental ET events and the link to the CTT conformational change that drives macroscopic properties (i.e., magnetoreception).
Date
2023-07-17
Citation:
APA:
Signorelli, Rachel Lee.
(July 2023).
Determination of the Role of Tyrosine-319 on the Efficiency of Photoinduced Radical Pairs in Avian Cryptochrome Photoreceptor Proteins Related to Magnetoreception
(Master's Thesis, East Carolina University). Retrieved from the Scholarship.
(http://hdl.handle.net/10342/13162.)
MLA:
Signorelli, Rachel Lee.
Determination of the Role of Tyrosine-319 on the Efficiency of Photoinduced Radical Pairs in Avian Cryptochrome Photoreceptor Proteins Related to Magnetoreception.
Master's Thesis. East Carolina University,
July 2023. The Scholarship.
http://hdl.handle.net/10342/13162.
April 29, 2024.
Chicago:
Signorelli, Rachel Lee,
“Determination of the Role of Tyrosine-319 on the Efficiency of Photoinduced Radical Pairs in Avian Cryptochrome Photoreceptor Proteins Related to Magnetoreception”
(Master's Thesis., East Carolina University,
July 2023).
AMA:
Signorelli, Rachel Lee.
Determination of the Role of Tyrosine-319 on the Efficiency of Photoinduced Radical Pairs in Avian Cryptochrome Photoreceptor Proteins Related to Magnetoreception
[Master's Thesis]. Greenville, NC: East Carolina University;
July 2023.
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Publisher
East Carolina University