Molecular Determinants of Phosphatidylinositol 4,5Bisphosphate (PI(4,5)P2) Binding to Transient Receptor Potential V1 (TRPV1) Channels [Lipids]

November 25th, 2014 by Poblete, H., Oyarzun, I., Olivero, P., Comer, J., Zuniga, M., Sepulveda, R. V., Baez–Nieto, D., Gonzalez Leon, C., Gonzalez–Nilo, F., Latorre, R.

Phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) has been recognized as an important activator of certain transient receptor potential (TRP) channels. More specifically, TRPV1 is a pain receptor activated by a wide range of stimuli. However, whether or not PI(4,5)P2 is a TRPV1 agonist remains open to debate. Utilizing a combined approach of mutagenesis and molecular modeling, we identified a PI(4,5)P2 binding site located between the TRP box and the S4-S5 linker. At this site, PI(4,5)P2 interacts with the amino acid residues R575 and R579 in the S4-S5 linker and with K694 in the TRP box. We confirmed that PI(4,5)P2 behaves as a channel agonist and found that R575, R579 and K694 mutations to alanine reduce PI(4,5)P2 binding affinity. Additionally, in silico mutations R575A, R579A and K694A showed that the reduction in binding affinity results from the delocalization of PI(4,5)P2 in the binding pocket. Molecular dynamics simulations indicate that PI(4,5)P2 binding induces conformational rearrangements of the structure formed by S6 and the TRP domain, which cause an opening of the lower TRPV1 channel gate.
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