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New Biological Frontiers Illuminated by Molecular Sensors and Actuators
Poster Abstracts
29-POS
Board 29
Functional Conformational Changes of Blue-light Sensing Cryptochrome
Chongjun Ma
, Pei Li, Yawei Dai, Yan-Wen Tan.
Fudan University, Shanghai, China.
Cryptochromes, a kind of blue-light sensing proteins, are best known to regulate the entrainment
of circadian rhythms responses in diverse organisms. More intriguingly, they are found to
involve in the sensing of magnetic fields for insects and small animals. Algae, plant and animal
cryptochromes possess vastly different size of carboxy-terminal (C-terminal) extensions, while
the C-terminal domain is found to be significant in the functional response of plant
cryptochromes. Here, we investigate the interaction partner, functional mechanism, and the
possible C-terminal conformational changes of an alga cryptochrome (aCry). Protein pull-down
assay is used to screen possible interaction partners of aCry, and a component of the circadian
rhythm was found to directly interact with aCry in a blue-light dependent manner. We use single
molecule Förster Resonance Energy Transfer (smFRET) to study the conformational changes of
aCry. In the dark, aCry stays in the close conformation as monomer. Exposure to blue-light
causes aCry to endure a conformational release of C-terminal domain from the PHR domain and
partial homodimerization. Chemical reduction of the cryptochrome cofactor, FAD, induces
further conformational extension in the presence and absence of blue-light.
30-POS
Board 30
Tuning the Temperature of Single Cells: a New Tool to Study Temperature Sensing
Hairong Ma
.
Drexel University, Philadelphia, USA.
Temperature fluctuation is a common environmental cue that can affect many essential cellular
activities including metabolism, proliferation, and apoptosis. Recent study shows that single cells
can directly sense the environmental temperature change and respond through metabolic
adjustment such as thermogenesis. Yet the mechanism of temperature sensing is largely
unknown and remains an intriguing problem. The effort is stymied by the lack of appropriate
tools that can induce a wide range of temperature perturbations in live cells with adequate time
resolution. To address this problem we have developed a novel platform combining infrared laser
induced temperature-jump (T-jump) and fluorescence live-cell imaging, whereupon we can tune
the temperature of single cells or cell populations up to 60 degrees Celsius with millisecond
resolved time resolution.