The bite of the Peruvian green velvet tarantula (Thrixopelma pruriens) delivers a venom designed to quickly shut down many of its victim’s major body functions at once. As we’ve seen in the U.S. when states try to accomplish the same thing in lethal injections for executions, it’s not easy to do. Perhaps tarantula venom can teach us how to save people rather than kill them. That’s what researchers at the University of Queensland in Brisbane have done by isolating a peptide toxin that can be used to develop a high-potency, non-addictive pain reliever.
In a study to be presented at this week’s Biophysical Society's 60th Annual Meeting in Los Angeles, the researchers will discuss their work with the ProTx-II molecule, which was identified in 2014 as a possible painkiller in the Peruvian green velvet tarantula’s venom. That was the easy part. The new challenge was to determine how the peptide identified pain receptors, interacted with them and shut them down without affecting any others.
The scientists used nuclear magnetic resonance spectroscopy to identify the structure of the ProTx-II molecule. They then used surface plasmon resonance, fluorescence and molecular simulations to track the action between ProTx-II cells and neuronal (nerve) cells.
What they found was that the key is in the NaV 1.7, a pain receptor located directly on the cell membrane. ProTx-II is attracted to the neuronal cell membrane, where it is then properly oriented before increasing its concentration of painkiller and then attaching to the membrane at the location of the NaV 1.7.
This is the first time researchers have looked at the neuronal cell membrane as a tool for precisely delivering a toxin. The knowledge of its role will help develop a synthetic version of ProTx-II with fewer side effects than opioids and less chance for addiction or developing a resistance to it.
Let’s hope this doesn’t result in the demise of too many Peruvian green velvet tarantulas, which are already smart enough to trick most humans by actually living in Chile.