Hua Yuan
Graduate Student

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I'm interested in protein structure and function, especially protein structure change in signal transduction. The main approach I'm using to solve protein structure is X-ray crystallography. It's well known that organisms need to adjust their behavior accordingly to different light environment. To sense the light signal, they need something like antenna. The protein I'm working on, Slr1694, is one of the many antenna molecules from cyanobacterium Synechocystis PCC6803. Wild type Synechocystis PCC6803 will move towards white light source. However, it moves away from the light when the gene encoding Slr1694 is knocked out. Protein sequence alignment analysis indicates that Slr1694 belongs to a newly discovered photoreceptor family: BLUF (sensors of blue-light using FAD) proteins. The absorption spectrum of purified Slr1694 undergoes a reversible red-shift upon illumination, which is very similar to other BLUF family members. And it's yellow because of the chromophore FAD. The big question of my research is to understand how Slr1694 transfers the light signal to the cell therefore the cell can decide to move towards or away from the light source. Specifically I'm asking: what are the molecular level events happening on Slr1694 upon receiving light signal and in the process of recovery; what other molecules does Slr1694 talk to; how those events help the signal transduction. The answers of these questions will help us understand the general mechanism of light signal sensing and transferring by photoreceptor.