Although many steps of the pathway were already known, new research from a team including Carnegie's Ying Sun and Zhiyong Wang fills in a missing gap about the mechanism through which brassinosteroids cause plant genes to be expressed.
Their research, which will be published online by Nature Cell Biology on January 23, has implications for agricultural science and, potentially, evolutionary research.
"Brassinosteroids are found throughout the plant kingdom and regulate many aspects of growth and development, as well as resistance from external stresses," said Wang. "Mutant plants that are deficient in brassinosteroids show defects at many phases of the plant life cycle, including reduced seed germination, irregular growth in the absence of light, dwarfism, and sterility."
Previous research had identified a pathway of chemical signals that starts when a brassinosteroid binds to a receptor on the surface of a plant cell and activates a cascade of activity that consists of adding and removing phosphates from a series of proteins.
When brassinosteroids are not present, a protein in this pathway called BIN2 acts to add phosphates to two other proteins called BZR1 and BZR2, which are part of a special class of proteins called transcription factors. The phosphates inhibit the transcription factors. But when a brassinosteroid binds to the cell-surface receptor, BIN2 is deactivated, and as a result phosphates are removed from the two transcription factors. As a result, BZR1 and BZR2 can enter the cell's nucleus, where they bind directly to DNA molecules and promote a wide variety of gene activity.
Before this new research, the protein that detaches the phosphates and allows BZR1 and BZR2 to work was unknown. Using an extensive array of research techniques, the team was able to prove that a protein called protein phosphatase 2A (PP2A) is responsible.
"We discovered that PP2A is a key component of the brassinosteroid signaling pathway," Wang said. "This discovery completes the core signaling module that relays extracellular brassinosteroids to cue activity in the nucleus."
Further research is needed to determine whether brassinosteroid binding activates PP2A, or just deactivates BIN2, thus allowing PP2A to do this job. Additionally, PP2A is involved in a plant's response to gravity and light, among other things.
This aspect of the brassinosteroid signaling pathway bears some surprising resemblances to signaling pathways found in many members of the animal kingdom. More research could demonstrate details of the evolutionary split between non-protozoan animals and plants.
This work was financially supported by the Division of Chemical Sciences, Geosciences, and Biosciences, Office of Basic Energy Sciences of the US Department of Energy, as well as by NIH, the National Science Foundation of China, and the Herman Frasch Foundation. Some of the researchers were supported by the China Scholarship Council. The UCSF Mass Spectrometry Facility, where some of the research was conducted, is supported by the Biomedical Research Technology Program of the National Centre for Research Resources, NIH.
The Carnegie Institution for Science (carnegiescience.edu) is a private, nonprofit organization headquartered in Washington, D.C., with six research departments throughout the U.S. Since its founding in 1902, the Carnegie Institution has been a pioneering force in basic scientific research. Carnegie scientists are leaders in plant biology, developmental biology, astronomy, materials science, global ecology, and Earth and planetary science.
Zhiyong Wang | EurekAlert!
Cells communicate in a dynamic code
19.02.2018 | California Institute of Technology
Studying mitosis' structure to understand the inside of cancer cells
19.02.2018 | Biophysical Society
For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.
In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...
Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale
Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...
For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.
But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...
Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.
The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...
Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters
Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...
15.02.2018 | Event News
13.02.2018 | Event News
12.02.2018 | Event News
19.02.2018 | Materials Sciences
19.02.2018 | Materials Sciences
19.02.2018 | Life Sciences