Two plant cell 'hotspots' tell the cell where to import its resources
Scientists in the Brandizzi lab are increasing our understanding of expand iconendocytosis, how plant cells import molecules from their surroundings.
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.
Now, Stefano and a team of scientists reveal one way how the expand iconendoplasmic reticulum (ER), the plant’s protein factory, is connected to the process. The study is in the journal Cell Reports.
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, www.pexels.com/photo/two-person-holding-white-and-black-android-smartphones-926984/
A new AI system, called DeepLearnMOR, can identify organelles and classify hundreds of microscopy images in a matter of seconds and with an accuracy rate of over 97%. The study illustrates the potential of AI to significantly increase the scope, speed, and accuracy of screening tools in plant biology.
The study reports that the activity levels of the carbon metabolism protein, G6PDH, are related to decreased production of pollen in bean flowers. As global temperatures rise, some bean crops, including Michigan-grown varieties, might be more sensitive to higher heat levels.
Evan Angelos and Hainan Zhao were recognized during a ceremony which took place online on Monday, April 19, 2021. The Anton Lang Memorial Fund was established in honor of the founding director of the MSU-DOE Plant Research Laboratory, who passed away in 1996.