Nav: Home

Combining on and off switches, one protein can control flowering in plants

August 06, 2018

MADISON, Wis. -- As plants stretch toward the summer sun, they are marching toward one of the most important decisions of their lives -- when to flower. Too early, and they might miss out on key pollinators. Too late, and an early frost could damage their developing seeds.

Farmers who rely on their crops to flower at just the right time can only sit and worry. It's up to the plants.

That decision of when to flower is ultimately made by cells that must stop sending out leaves in order to start producing flowers. Scientists typically think of these critical decisions about cell fate as being controlled by the balance between one group of regulating proteins that accelerate cells toward one fate and other proteins that keep the brakes on. When the brake is released at the right cue, the cell marches toward its destiny as leaf, or flower.

But new research published Aug. 6 in the journal Nature Genetics by University of Wisconsin-Madison biologists has discovered a previously unknown mechanism for controlling cellular decisions, one which combines an on-and-off switch in a single protein. Professor of Genetics and Wisconsin Institute for Discovery researcher Xuehua Zhong and her lab found that the protein EBS can bind to two different chemical modifications on histones, proteins that DNA wraps around, either promoting or preventing the transition to flowering in plants.

Because the basic building blocks of EBS are found across plants and animals, this style of regulating crucial decisions about development and tissue generation is likely to be widespread. The researchers say that this linking of a developmental on-and-off switch in one protein provides opportunities for improving crops and could also help scientists study diseases like cancer.

Every organism starts out as a single cell, which means that a cell must be able to express both flower and leaf genes, although not at the same time. These young cells are undecided about their fate.

"It's like a first-year freshman. They have not declared a major yet," says Zhong. "So how do you maintain this undecided state? One way is what we call epigenetics."

Epigenetic regulation uses chemical decorations on DNA to help control which genes are active and which are shut off. Regulatory proteins can bind to activating or repressing chemical marks to promote or restrict which genes are turned on, which in turn controls what type of tissue a cell may become, or how an organism will change its growth.

Typically, gene activation is controlled by one protein, while another protein will inhibit the gene's expression. But Zhong's lab found that EBS is different.

"This one protein has domains that can read both activating and repressing marks, and then make the switch to turn on or turn off," says Shuiming Qian, a scientist in Zhong's lab who led the work.

"There have been proteins that can bind multiple modifications at once, but we've never seen one that can bind both repressive and active marks at the same time," adds Ray Scheid, a graduate student in the Zhong lab who contributed to the study. The UW-Madison researchers also collaborated with scientists at the Chinese Academy of Sciences to study the structure of EBS.

Plant scientists have long known that if EBS is absent, plants flower early. The research team found that if they disrupt the ability of EBS to bind to epigenetic modifications -- either repressive or activating marks -- flowering still occurs early, showing that the balance between on and off is crucial for EBS to work at all.

Zhong's lab also showed that when it is time to flower, EBS changes its shape, which makes it more strongly attach to the activating modifications. That change from "off" to "on" lets EBS turn on a set of genes that put the flowering program into action.

The joining of an on-and-off switch in a single protein provides flexibility in making key decisions about cell fate and development, says Zhong. The research team also sees opportunities for research and, one day, applications based on influencing how cells decide what to become through the control of just one protein.

One application that comes to mind for Zhong is based on what EBS is already good at -- controlling flowering.

"In Wisconsin, we have very short growing seasons," says Zhong. "If we can reduce a plant's life cycle and complete the season earlier, that could be very important for many crops."
-end-
--Eric Hamilton, (608) 263-1986, eshamilton@wisc.edu

This work was supported by the National Science Foundation Career Program (grant MCB-1552455), the National Institutes of Health-MIRA (grant R35GM124806), National Institutes of Health (grant GM059785-15/P250VA), the National Institutes of Health National Cancer Institute (grant R01CA193481), the Chinese National Key R&D Program (grant 2016YFA0503200), National Natural Science Foundation of China (grants 31622032 and 31770782), the Chinese Academy of Sciences and the Alexander von Humboldt Foundation.

University of Wisconsin-Madison

Related Proteins Articles:

Discovering, counting, cataloguing proteins
Scientists describe a well-defined mitochondrial proteome in baker's yeast.
Interrogating proteins
Scientists from the University of Bristol have designed a new protein structure, and are using it to understand how protein structures are stabilized.
Ancient proteins studied in detail
How did protein interactions arise and how have they developed?
What can we learn from dinosaur proteins?
Researchers recently confirmed it is possible to extract proteins from 80-million-year-old dinosaur bones.
Relocation of proteins with a new nanobody tool
Researchers at the Biozentrum of the University of Basel have developed a new method by which proteins can be transported to a new location in a cell.
Proteins that can take the heat
Ancient proteins may offer clues on how to engineer proteins that can withstand the high temperatures required in industrial applications, according to new research published in the Proceedings of the National Academy of Sciences.
Designer proteins fold DNA
Florian Praetorius and Professor Hendrik Dietz of the Technical University of Munich have developed a new method that can be used to construct custom hybrid structures using DNA and proteins.
The proteins that domesticated our genomes
EPFL scientists have carried out a genomic and evolutionary study of a large and enigmatic family of human proteins, to demonstrate that it is responsible for harnessing the millions of transposable elements in the human genome.
Rare proteins collapse earlier
Some organisms are able to survive in hot springs, while others can only live at mild temperatures because their proteins aren't able to withstand such extreme heat.
How proteins reshape cell membranes
Small 'bubbles' frequently form on membranes of cells and are taken up into their interior.

Related Proteins Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Changing The World
What does it take to change the world for the better? This hour, TED speakers explore ideas on activism—what motivates it, why it matters, and how each of us can make a difference. Guests include civil rights activist Ruby Sales, labor leader and civil rights activist Dolores Huerta, author Jeremy Heimans, "craftivist" Sarah Corbett, and designer and futurist Angela Oguntala.
Now Playing: Science for the People

#521 The Curious Life of Krill
Krill may be one of the most abundant forms of life on our planet... but it turns out we don't know that much about them. For a create that underpins a massive ocean ecosystem and lives in our oceans in massive numbers, they're surprisingly difficult to study. We sit down and shine some light on these underappreciated crustaceans with Stephen Nicol, Adjunct Professor at the University of Tasmania, Scientific Advisor to the Association of Responsible Krill Harvesting Companies, and author of the book "The Curious Life of Krill: A Conservation Story from the Bottom of the World".