Plunk a houseplant near a window, and often that plant will bend eagerly toward the light to soak up as much energy as possible. A protein cranked out by plant cells dubbed ³phototropin² is key to this action. But how does this protein manage the growth of a plant toward sunlight?
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Scientists probe the mystery of phototropism. From the University of Kansas, this is Research Matters. I’m Brendan Lynch.
Plunk a houseplant near a window, and often that plant will grow eagerly toward the light. Phototropism is the name of this process. Carey Johnson, chemistry professor at KU, is investigating how a protein cranked out by plant cells called “phototropin” is key to this action.
Johnson: Phototropin has in it two domains called LOV domains. Love stands for light ocygyn light voltage. It’s the LOV domain that absorbs light — specifically blue light. Somehow a signal is relayed to the rest of the protein and then onto other parts of the plant. And it’s not really understood how that signal is relayed.
Funded by a new $426,000 grant from the National Science Foundation, Johnson leads a new international effort to better grasp the process.
Johnson: We extract the protein from algae or we can synthesize the protein by expression in bacteria using recombinant DNA methods. We want to see how this works using florescent spectroscopy, which is the interaction of molecules with light and then their reemission of light.
Using fluorescent dyes, laser beams and light sensors, Johnson and his team will track amino acids associated with phototropin’s LOV domains.
Johnson: The most challenging part will be to interpret what the signals that we see mean in terms of how the protein works. That’s often the hardest part to understand — what the signals are telling us. Then we’ll design a subsequent experiment to see if we got it right or not.
For more on phototropism, log on to Research Matters dot KU dot EDU. For the University of Kansas, I’m Brendan Lynch.