Scientists have determined how Venus fly trap plants (Dionaea muscipula) carry out their characteristic snapping mechanism, where they ‘snap shut’ when an insect or an arachnid enters. The snapping mechanism is a combination of an interaction between elasticity, turgor and growth.
This relates to a mechanosensitive ion channel. What is of interest is that this mechanism is related to channels found in variety of other organisms. Mechanosensitivity is a specific response to mechanical stimulation and this response is common to a wide variety of different types of cells.
The research comes from the Scripps Research Institute and the focus has been with a three-dimensional structure of a protein channel named ‘Flycatcher1’ in relation to the plant. This channel enables Venus fly trap plants to snap shut in response to prey. The Venus flytrap is found in nitrogen- and phosphorus-poor environments, such as bogs and wet savannahs (the insect prey provides the needed nitrogen for protein formation that the soil cannot).
The structure of the interestingly named Flycatcher1 answers a longstanding question about the remarkable sensitivity of the touch response of Venus fly traps. The trigger point is the mechanosensitive ion channels. These are a little like tunnels and they span the membranes of cells.
When jostled by movement, the channels open up, allowing charged molecules rush across. In response, cells then alter their behaviour. To gain an insight into this process, the researchers deployed cryo-electron microscopy. This is a new technique and one capable of revealing the locations of atoms within a frozen protein sample.
This level of analysis showed that Flycatcher1 is similar to bacterial MscS proteins and is presented as seven groups of identical helices surrounding a central channel. However, Flycatcher1 has an atypical linker region that extends outward from each group of helices. Similar to a switch, each linker can be flipped up or down.
By studying mutations, it was established that the conformations of these seven linkers is relevant for how the channel works.
The structure additionally provides researchers an understanding of how similar proteins in other organisms, including plants and bacteria, plus proteins in the human body, that posses similar functions might operate. This is connected to understanding how cells and organisms respond to touch and pressure.
The ability for cells to sense pressure and movement is part of people’s senses of touch and hearing. When this does not work as intended this can lead to complications with a range of internal body processes, such as the ability of the bladder to sense that it is full or the ability of lungs to sense how much air is being breathed in.
The research appears in the journal Nature Communications, titled “Structural insights into the Venus flytrap mechanosensitive ion channel Flycatcher1.”
