Flycatcher1, an appropriately named protein channel that may allow Venus fly trap plants to snap shut in reaction to prey, has been shown in three dimensions by scientists. The anatomy of Flycatcher1 sheds insight on long-standing problems concerning Venus fly traps’ incredibly acute touch reaction. The structure also helps researchers understand how comparable proteins in animals such as plants and bacteria, as well as proteins in the human body with similar activities (known as mechanosensitive ion channels), work.
The three-dimensional structure of Flycatcher1, a protein channel that may allow Venus fly trap plants to snap shut in reaction to prey, has been unveiled by Scripps Research. The structure of Flycatcher1, which was published in Nature Communications on February 14, sheds insight on long-standing problems concerning Venus fly traps’ incredibly acute touch sensitivity. The structure also helps researchers understand how comparable proteins in animals such as plants and bacteria, as well as proteins in the human body with similar activities (known as mechanosensitive ion channels), work.
“Despite how different Venus fly traps are from people, researching the structure and function of these mechanosensitive channels offers us a larger framework for understanding how cells and animals react to touch and pressure,” explains Scripps Research professor Andrew Ward, PhD, co-senior author.
“Every new mechanosensitive channel that we study advances our understanding of how these proteins sense force and translate it to action, revealing more about human biology and health,” says co-senior author Ardem Patapoutian, PhD, a Scripps Research professor who won the Nobel Prize in Physiology or Medicine for his work on mechanosensitive channels that allow the body to sense touch and temperature.
Mechanosensitive ion channels resemble tunnels that run across cell membranes. When the channels are jostled by movement, they open, allowing charged molecules to pass through. Cells change their activity in reaction to this, such as a neuron signaling its neighbor. Cells’ capacity to detect pressure and movement is critical not just for people’s senses of touch and hearing, but also for a variety of internal bodily functions, such as the bladder’s ability to sense when it’s full and the lungs’ ability to sense how much air is being inhaled.
Scientists had previously focused on three ion channels in Venus fly traps that were considered to be linked to the plant’s ability to snap its leaves shut when its sensitive trigger hairs were touched. Researchers were drawn to Flycatcher1 because its DNA sequence resembled that of the MscS family of mechanosensitive channels discovered in bacteria.
“The fact that numerous varieties of this channel have been identified throughout evolution tells us that it must have some basic, vital capabilities that have been preserved in diverse sorts of creatures,” says Sebastian Jojoa-Cruz, a Scripps Research graduate student.
The researchers analyzed the exact arrangement of molecules that create the Flycatcher1 protein channel in Venus fly trap plants using cryo-electron microscopy, a cutting-edge technology that exposes the positions of atoms inside a frozen protein sample. Flycatcher1 is similar to bacterial MscS proteins in many aspects, with seven groups of identical helices encircling a central channel. Flycatcher1 contains a peculiar linker region extending outward from each set of helices, unlike other MscS channels. Each linker may be flicked up or down like a switch. When the scientists deduced Flycatcher1’s structure, they discovered six linkers in the down position and just one flipped up.
“The design of Flycatcher1’s channel core was comparable to other channels that have been studied for years, but the linker regions were unexpected,” says Kei Saotome, PhD, co-first author of the current work and former postdoctoral research associate at Scripps Research.
The researchers changed the linker to disrupt the up position in order to better understand the function of these switches. They discovered that Flycatcher1 no longer worked as it should in response to pressure; the channel stayed open for extended periods of time when it should have closed when pressure was removed.
“The severe impact of this mutation informs us that the conformations of these seven linkers are likely crucial for how the channel operates,” explains Swetha Murthy, PhD, co-senior author and former Scripps Research postdoctoral research associate.
The study team is planning additional investigations on the function of Flycatcher1 now that the molecular structure has been determined, in order to better understand how various conformations impact its function. More research is required to identify whether Flycatcher1 is the only channel responsible for the Venus fly trap leaves snapping shut, or whether other putative channels play a supporting role.
Authors of the article “Structural insights into the Venus flytrap mechanosensitive ion channel Flycatcher1” include Che Chun Alex Tsui and Wen-Hsin Lee of Scripps Research, as well as Mark Sansom of the University of Oxford.
The National Institutes of Health (R01 HL143297, R01 HL143297), the Ray Thomas Edwards Foundation, the Wellcome Trust (grant 208361/Z/17/Z), the Biotechnology and Biological Sciences Research Council (grants BB/N000145/1 and BB/R00126X/1), the Engineering and Physical Sciences Research Council (grant EP/R004722/1), the Engineering and Physical Sciences Research Council (grant EP/R004722/1