Limits...
Structural insights into the mechanism of activation of the TRPV1 channel by a membrane-bound tarantula toxin.

Bae C, Anselmi C, Kalia J, Jara-Oseguera A, Schwieters CD, Krepkiy D, Won Lee C, Kim EH, Kim JI, Faraldo-Gómez JD, Swartz KJ - Elife (2016)

Bottom Line: We also provide improved structures of TRPV1 with and without the toxin bound, and investigate the interactions of DkTx with the channel and membranes.Finally, we find that the toxin disrupts a cluster of hydrophobic residues behind the selectivity filter that are critical for channel activation.Collectively, our findings reveal a novel mode of toxin-channel recognition that has important implications for the mechanism of thermosensation.

View Article: PubMed Central - PubMed

Affiliation: Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States.

ABSTRACT
Venom toxins are invaluable tools for exploring the structure and mechanisms of ion channels. Here, we solve the structure of double-knot toxin (DkTx), a tarantula toxin that activates the heat-activated TRPV1 channel. We also provide improved structures of TRPV1 with and without the toxin bound, and investigate the interactions of DkTx with the channel and membranes. We find that DkTx binds to the outer edge of the external pore of TRPV1 in a counterclockwise configuration, using a limited protein-protein interface and inserting hydrophobic residues into the bilayer. We also show that DkTx partitions naturally into membranes, with the two lobes exhibiting opposing energetics for membrane partitioning and channel activation. Finally, we find that the toxin disrupts a cluster of hydrophobic residues behind the selectivity filter that are critical for channel activation. Collectively, our findings reveal a novel mode of toxin-channel recognition that has important implications for the mechanism of thermosensation.

No MeSH data available.


Improvements in the newly refined structural models of apo and DkTx-bound TRPV1.Final ROSETTA models of apo TRPV1 (A) and of the TRPV1-DkTX complex (B) are shown color-coded according to the change in the calculated ProQM score relative to the initial structures deposited in the PDB (entries 3J5P and 3J5Q, respectively). Blue represents an improved score in the ROSETTA model and/or a region without assigned backbone or side-chain coordinates in the initial structures. Red represents a worse score in the ROSETTA model.DOI:http://dx.doi.org/10.7554/eLife.11273.013
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4764579&req=5

fig2s3: Improvements in the newly refined structural models of apo and DkTx-bound TRPV1.Final ROSETTA models of apo TRPV1 (A) and of the TRPV1-DkTX complex (B) are shown color-coded according to the change in the calculated ProQM score relative to the initial structures deposited in the PDB (entries 3J5P and 3J5Q, respectively). Blue represents an improved score in the ROSETTA model and/or a region without assigned backbone or side-chain coordinates in the initial structures. Red represents a worse score in the ROSETTA model.DOI:http://dx.doi.org/10.7554/eLife.11273.013

Mentions: Further improvements of the ROSETTA models for apo and DkTx-bound TRPV1 focused on the configuration of the side-chains poorly resolved in the EM map (approximately 80% of the side-chain atoms). An ensemble of 12,000 models, weighted by the ROSETTA energy function, were generated in each case, and the most representative among these were identified through a clustering analysis. The selected models for apo and DkTx-bound TRPV1 further improve the ROSETTA score without compromising the quality of the fit to the experimental cryo-EM maps (Figure 2—figure supplement 2). Relative to the structures deposited in the PDB, these optimized models also showed a generalized improvement in ProQM per-residue scores (Ray et al., 2010) (Figure 2—figure supplement 3), in addition to the improved MolProbity global scores mentioned above (Tables 1, 2). Both models are publicly available upon request to the authors.


Structural insights into the mechanism of activation of the TRPV1 channel by a membrane-bound tarantula toxin.

Bae C, Anselmi C, Kalia J, Jara-Oseguera A, Schwieters CD, Krepkiy D, Won Lee C, Kim EH, Kim JI, Faraldo-Gómez JD, Swartz KJ - Elife (2016)

Improvements in the newly refined structural models of apo and DkTx-bound TRPV1.Final ROSETTA models of apo TRPV1 (A) and of the TRPV1-DkTX complex (B) are shown color-coded according to the change in the calculated ProQM score relative to the initial structures deposited in the PDB (entries 3J5P and 3J5Q, respectively). Blue represents an improved score in the ROSETTA model and/or a region without assigned backbone or side-chain coordinates in the initial structures. Red represents a worse score in the ROSETTA model.DOI:http://dx.doi.org/10.7554/eLife.11273.013
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4764579&req=5

fig2s3: Improvements in the newly refined structural models of apo and DkTx-bound TRPV1.Final ROSETTA models of apo TRPV1 (A) and of the TRPV1-DkTX complex (B) are shown color-coded according to the change in the calculated ProQM score relative to the initial structures deposited in the PDB (entries 3J5P and 3J5Q, respectively). Blue represents an improved score in the ROSETTA model and/or a region without assigned backbone or side-chain coordinates in the initial structures. Red represents a worse score in the ROSETTA model.DOI:http://dx.doi.org/10.7554/eLife.11273.013
Mentions: Further improvements of the ROSETTA models for apo and DkTx-bound TRPV1 focused on the configuration of the side-chains poorly resolved in the EM map (approximately 80% of the side-chain atoms). An ensemble of 12,000 models, weighted by the ROSETTA energy function, were generated in each case, and the most representative among these were identified through a clustering analysis. The selected models for apo and DkTx-bound TRPV1 further improve the ROSETTA score without compromising the quality of the fit to the experimental cryo-EM maps (Figure 2—figure supplement 2). Relative to the structures deposited in the PDB, these optimized models also showed a generalized improvement in ProQM per-residue scores (Ray et al., 2010) (Figure 2—figure supplement 3), in addition to the improved MolProbity global scores mentioned above (Tables 1, 2). Both models are publicly available upon request to the authors.

Bottom Line: We also provide improved structures of TRPV1 with and without the toxin bound, and investigate the interactions of DkTx with the channel and membranes.Finally, we find that the toxin disrupts a cluster of hydrophobic residues behind the selectivity filter that are critical for channel activation.Collectively, our findings reveal a novel mode of toxin-channel recognition that has important implications for the mechanism of thermosensation.

View Article: PubMed Central - PubMed

Affiliation: Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States.

ABSTRACT
Venom toxins are invaluable tools for exploring the structure and mechanisms of ion channels. Here, we solve the structure of double-knot toxin (DkTx), a tarantula toxin that activates the heat-activated TRPV1 channel. We also provide improved structures of TRPV1 with and without the toxin bound, and investigate the interactions of DkTx with the channel and membranes. We find that DkTx binds to the outer edge of the external pore of TRPV1 in a counterclockwise configuration, using a limited protein-protein interface and inserting hydrophobic residues into the bilayer. We also show that DkTx partitions naturally into membranes, with the two lobes exhibiting opposing energetics for membrane partitioning and channel activation. Finally, we find that the toxin disrupts a cluster of hydrophobic residues behind the selectivity filter that are critical for channel activation. Collectively, our findings reveal a novel mode of toxin-channel recognition that has important implications for the mechanism of thermosensation.

No MeSH data available.