Experts identify a molecular switch that controls plant photosynthesis

Experts identify a molecular switch that controls plant photosynthesis. Experts at Washington State University are providing incredible insight into the complex system of plant photosynthesis. In a groundbreaking study, the researchers have identified a lipid that switches photosynthesis off when plants have harvested a sufficient amount of sunlight.

While it is known that plants capture light energy and transform it into chemical energy, the mechanisms underlying this process are not entirely clear. The WSU researchers created a tool to gain a better understanding of how lipids interact with proteins during photosynthesis in plants. They identified a lipid that controls the timing when a photosynthetic protein switches from harnessing light energy to blocking its flow. 

“There’s a lot of potential danger with photosynthesis,” said study lead author Professor Helmut Kirchhoff. “If plants take in light energy that isn’t used properly for their metabolism, it can poison the plant and kill cells. The switch of light-harvesting proteins is essential to protect the system when there’s too much light available.”

Prior to this study, it was a mystery how plants avoided taking in toxic amounts of sunlight.

Lipids are molecules in cell membranes that interact with the proteins found in chloroplasts, where photosynthesis takes place. 

The researchers found that one specific type of lipid, a non-bilayer lipid, appears to initiate a transition made by the light-harvesting protein when the plant has received enough light and needs to dissipate some of the excess energy.

“We were suspicious that this non-bilayer lipid had a role in controlling the structure and function of membrane proteins,” explained Professor Kirchhoff. “We knew it had to have a function to be there because it’s the most abundant lipid in photosynthetic membranes. We just didn’t know exactly what that role would be.”

As Earth’s climate continues to change and the human population explodes, it is critically important to find ways to grow more crops with fewer resources. According to Professor Kirchhoff, the findings of this study may ultimately lead to methods for optimizing plant photosynthesis in specific environments, so that excess energy does not have to be wasted.

“We’re still very early on, but we’re excited by what we’ve found in this paper, and we’ll continue to use our new process to study other lipid-protein interactions to see what else we can learn.”

The study is published in the Journal of Biological Chemistry.

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By Chrissy Sexton, Earth.com Staff Writer