Single-Cell Biophysics: Measurement, Modulation, and Modeling

Single-Cell Biophysics: Measurement, Modulation, and Modeling

Poster Abstracts

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

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