Two plant cell 'hotspots' tell the cell where to import its resources
During endocytosis, the cell identifies an external molecule. The cell's outer cover, the plasma membrane, folds inwards, luring in that molecule. The folded part then pinches off and takes the surrounding cargo to its destination inside the cell.
Endocytosis is essential for plant health. It is how cells fine-tune the amounts of molecules they import. Otherwise, plants can get damaged. For example, experiments where the process is faulty leads to smaller roots and shoots.
“We do not still fully know how this process works. We want to understand how it talks with other parts of the cell and hands them the imported molecules,” says Giovanni Stefano. Stefano is a Research Assistant Professor in the lab of Federica Brandizzi.
The Science: 'hotspots' trigger endocytosis
The scientists focused on two proteins, called VAP27-1 and VAP27-3. Both are found at the contact sites between the ER and the plasma membrane.
“It seems that these two proteins bridge the ER with the endocytic membranes through an interaction that involves lipids,” Stefano says. “We are the first to show, through various analyses and microscopic imaging, how these proteins impact endocytosis.”
The VAP proteins work like hotspots that tell the cell where endocytosis should take place. They do it by recruiting a component, known as clathrin, which triggers endocytosis.
And the VAP proteins seem to be a crucial part of the process.
“When we remove them from a plant, endocytosis and growth rates become unbalanced,” Stefano says. “But endocytosis is only partially compromised. We are not sure yet if there are other components that explain why it still works to a certain degree.”
The two VAP proteins in the study belong to a larger collection of four proteins, all called VAP.
“All four proteins are found at the contact site between the ER and the plasma membrane,” Stefano says. “We think they play overlapping roles in endocytosis. Each one might target a different plant tissue.”
Banner image by rawpixel.com, CC0 License
Share this story
The protein, peroxiredoxin Q, is known to maintain a healthy balance of chemicals and energy levels in chloroplasts. The new research shows the protein also impacts the system that produces chloroplast membranes.
The CAMTA system - which is known to protect plants from cold weather - plays a newly discovered role: when bacteria invade a leaf, CAMTA warns neighboring, unaffected leaves to prepare for invasion.
When algae get stressed, they hibernate and store energy in forms that we can use to make biofuels. Understanding how stress impacts algal hibernation could help scientists lower the cost of biofuels production.