Compared to a wild-type Arabidopsis (WT, left), plants that do not have UBP12 and UBP13 (Nos. 1-7 and Nos. 12-8, in the center) or BRI1 (bri1-null, right) have extremely high growth. delayed. Credit: EMBO reports (2022). DOI: 10.15252 / embr.202153354
Scientists have revealed two enzymes that regulate the degradation of proteins in the cell membrane of plants and have established their role in the growth and development of plants.
Ubiquitin is a small regulatory protein found in most cells of eukaryotic organisms. It is vital for altering the function of other proteins, and is primarily involved in the degradation of proteins and the localization of proteins within the cell. Ubiquitin regulates these functions by binding to and separating from the target protein, a process called ubiquitination.
Scientists from Japan, Belgium and the United States, led by Associate Professor Takeo Sato of Hokkaido University, have discovered the first examples of deubiquitin enzymes in plants that act on cell membrane proteins. His findings, published in the journal EMBO reportsdetail the function of these proteins.
The addition of ubiquitin to target proteins is catalyzed by enzymes called ubiquitin ligases, and the reverse process, the removal of ubiquitin from target proteins, is catalyzed by deubiquitinase enzymes (DUBs). It was not known which plant DUBs could directly remove ubiquitin from membrane proteins. This lack of knowledge meant that the regulation of the stability of membrane proteins was not fully understood.
In normal cells (left), BRI1 (fluorescent yellow) is present mainly in the cell membrane and some BRI1 is degraded in vacuoles. In cells lacking UBP12 and UBP13, the concentration of BRI1 in vacuoles increases sharply as a large proportion is degraded. Credit: EMBO reports (2022). DOI: 10.15252 / embr.202153354
The team showed that two of the Arabidopsis thaliana DUBs, UBP12 and UBP13, go directly to the plant hormone receptor located on the cell membrane known as BRI1.
BRI1 is vital for the detection of brassinosteroids (BR), steroid phytohormones that are essential for growth and development. Normally, when BRI1 detects BR, it activates a pathway that regulates gene expression in the nucleus. Cellular BRI1 abundance is crucial to accurately mediate the BR signal, although the regulatory mechanism of how BRI1 abundance in cells is optimized (tuned) was unclear. The scientists showed that UBP12 and UBP13 desubiquitized and stabilized BRI1.
In their experiments, they showed that Arabidopsis thaliana plants that did not have the ability to express UBP12 and UBP13 were highly despised and clearly less sensitive to BR. When a BRI1 mutant, which could not be ubiquitinated, was introduced into these plants with UBP12 and UBP13 deficiency, growth defects were partially restored. Specifically, UBP12 and UBP13 are oriented and act on ubiquitinated BRI1.
The study showed that UBP12 and UBP13 are key regulators of plant growth through their interaction with BRI1. The study also provided information on how the stability of membrane proteins is maintained; however, more research is required to fully understand the dynamics of BRI1 within the cell. Finally, the findings provide evidence that plant DUBs have similar roles to mammalian DUBs.
Researchers reveal the role of the pair of ubiquitin ligase and deubiquitinase E3 in the regulation of abscisic acid perception. More information: Yongming Luo et al, UBP12 and UBP13 deubiquitinating enzymes stabilize the brassinosteroid receptor BRI1, EMBO reports (2022). DOI: 10.15252 / embr.202153354 Provided by Hokkaido University
Citation: New insights into the effects of membrane proteins on plant growth (2022, June 3) retrieved June 3, 2022 from
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