By Jamie Martin
The research team identifies a metal-based sensing system in plant cell receptors. The research team from the Institute of Transformative Biomolecules at Nagoya University, along with collaborators from RIKEN and The University of Osaka, has identified new mechanism plants use to sense stress. Their findings were published in Nature Communications.
Plants constantly monitor their surroundings to respond to stress factors such as pathogens and environmental changes. One key molecule involved in these responses is hydrogen peroxide, which acts as a signaling compound within plant cells.
Previously, scientists believed that plants detected hydrogen peroxide using cysteine residues. However, this new study shows that plants rely on a copper-based system instead.
The research focused on a receptor known as CARD1 or HPCA1. This receptor belongs to a group of proteins that help plants sense changes in their environment. The team discovered that CARD1 contains a copper ion attached to histidine residues on its surface.
This copper site plays a major role in detecting hydrogen peroxide. When the molecule is present, it reacts with copper, allowing the plant to recognize the signal and initiate defense actions.
The study also confirmed that cysteine residues are not essential for sensing hydrogen peroxide. Instead, they support the structure of the receptor, helping it maintain stability.
"The results showed that when the copper-binding site is disrupted, plants lose their ability to respond to H₂O₂ signals," said Anuphon Laohavisit, lead author and designated associate professor at the WPI-ITbM. "In contrast, mutations in cysteine residues had little effect on signaling, indicating that their primary role is structural rather than signaling."
Further analysis suggests that the reaction involves a change in the chemical state of copper. This may directly activate signaling or produce other molecules that trigger responses inside the plant.
The researchers also believe that a different system may be responsible for detecting quinones, another group of stress-related compounds.
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