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Single-Cell Biophysics: Measurement, Modulation, and Modeling
Poster Abstracts
133
70-POS
Board 35
Blue-light Dependent Conformational Change of Cryptochromes
Li Pei
1
, Chongjun Ma
1
, Huaqiang Cheng
1
, Xuanxuan Li
2
, Haiguang Liu
2
, Yanwen Tan
1
.
1
Fudan University, Shanghai, China,
2
Beijing Computational Science Research Center, Beijing,
China.
Cryptochromes are a kind of blue-light photoreceptors, which entrain the circadian rhythms in
diverse organisms. Cryptochromes have also been reported to sense magnetic fields for some
species such as fruit fly, butterfly and pigeons. Algae, plant and animal cryptochromes possess
conserved photolyase homology region (PHR) domain and vastly different size carboxyl-
terminal (C-terminal) extensions. The C-terminal conformations have been hypothesized to
participate in the blue-light response signaling mechanism. Here, we use single molecule Förster
Resonance Energy Transfer (smFRET) and Small-Angle X-ray Scattering (SAXS) to investigate
the C-terminal conformational changes of cryptochromes. The FRET efficiency distributions
indicate that cryptochromes prefer to stay in close conformation in dark. After exposure to blue-
light, C-terminal will be released from PHR domain. SAXS measurements are consistent with
this result, which reveal the radius of gyration changes of cryptochromes after sensing the blue
light. Furthermore, the blue-light dependent homodimerization has been confirmed by smFRET
assays, size exclusion chromatography and Native-PAGE assay.
Key Words
：
Cryptochromes, smFRET, SAXS, Conformational change, Dimerization