In light of new findings by Scripps Research scientists, the way the jaws of the Venus flytrap snap shut may be due to a microscopic touch sensor that is highly sensitive to pressure. Remarkably, similar sensors, called mechanosensors, are responsible for detecting force in the human body, enabling fundamental processes like touch sensation on our skin, blood pressure maintenance and bladder control.
Structural and computational biologists used a cutting-edge technique called cryo-electron microscopy. Taking a frozen biological sample, they were able to reveal the precise arrangement of atoms in a protein of the plant called Flycatcher1. Previous work by scientists in the lab of professor Ardem Patapoutian, PhD, in collaboration with researchers from the Salk Institute for Biological Studies, identified three different genes in the trigger hairs of these plants that would code for mechanically activated protein sensors.
In a recent study published in Nature Communications, Patapoutian’s group teamed up with the lab of Scripps Research professor Andrew Ward, PhD, to zoom in further on Flycatcher1. Out of the three mechanosensors previously discovered, the scientists recognized that Flycatcher1 is both very abundant in the trigger hairs of the flytrap and shares some genetic similarities to a sensor found in bacteria. The preservation of these sensor genes throughout the course of evolution in diverse organisms usually gives researchers a clue that those genes are responsible for a fundamental function.
To probe this function, the team disrupted the genetic code of one the sensor’s regions that acts like a molecular switch. By keeping this switch off, the researchers discovered that Flycatcher1 was no longer activated when prompted with the application of pressure. This would suggest that this molecular switch, and the Flycatcher1 sensor more broadly, may be critical for helping the plant’s trap to close shut when visited by a curious fly.
While the Flycatcher1 protein is specific to plants, the sensor may share similar mechanisms at the molecular level to the PIEZO family of mechanosensors that enable touch sensation in the human body. Additionally, PIEZO proteins have been identified in the thale cress plant, where they appear to be essential for root growth and position.
“Despite how different Venus flytraps are from humans, studying the structure and function of these mechanosensitive channels gives us a broader framework for understanding the ways that cells and organisms respond to touch and pressure,” says Ward. In addition to helping us better understand plants, these studies also provide valuable insights about how various force-activated proteins might operate in human tissues, allowing researchers to better determine disease processes and devise potential medical therapies that involve mechanical stimulation.
These protein sensors are officially called mechanosensitive ion channels. They are molecular tunnels that span a cell’s outer layer (membrane). When pressure is applied, the channels open, allowing electrically-charged molecules (ions) to rush across. In response, cells then alter their behavior, such as send a nerve impulse, in the case of the human nervous system, or snap leaves shut, in the case of carnivorous plants.