What can spider venom tell us about how we sense heat?
Researchers have used a toxin from a spider to study the structure of a heat sensing protein from mammals.
Humans and other mammals sense heat using a protein called the transient receptor potential vanilloid (TRPV1) channel. This protein is found in the membranes of a particular type of nerve cell, and it forms a pore that allows certain ions to pass through the membrane. Along with sensing heat, TRPV1 can also be activated by a toxin called double-knot toxin — which is found in spider venom — and by capsaicin, the active ingredient in chilli peppers.
One way to investigate how a protein works is to study its three-dimensional (3D) structure. Here, Chanhyung Bae, Claudio Anselmi and colleagues use a technique called nuclear magnetic resonance (NMR) spectroscopy to produce a detailed model of the 3D structure of double-knot toxin. This model is then combined with 3D maps of TRPV1 from previous studies to predict where the toxin binds to TRPV1. This suggests that the toxin binds to a section of TRPV1 that is buried within the membrane. Moreover, the new models highlight a ‘hydrophobic’ region of the TRPV1 channel that may work as the heat sensor.
Together, Bae, Anselmi and colleagues findings reveal a new way in which a toxin can bind to a target protein in membranes. The next step is to test the idea that the hydrophobic region identified in this work is the part of TRPV1 that senses heat.
To find out more
Read the eLife research paper on which this eLife digest is based: “Structural insights into the mechanism of activation of the TRPV1 channel by a membrane-bound tarantula toxin” (February 10, 2015).