Our understanding of the general principles of the polymodal regulation of transient receptor potential (TRP) ion channels has grown impressively in recent years as a result of intense efforts in protein structure determination by cryo-electron microscopy. In particular, the high-resolution structures of various TRP channels captured in different conformations, a number of them determined in a membrane mimetic environment, have yielded valuable insights into their architecture, gating properties and the sites of their interactions with annular and regulatory lipids. The correct repertoire of these channels is, however, organized by supramolecular complexes that involve the localization of signaling proteins to sites of action, ensuring the specificity and speed of signal transduction events. As such, TRP ankyrin 1 (TRPA1), a major player involved in various pain conditions, localizes into cholesterol-rich sensory membrane microdomains, physically interacts with calmodulin, associates with the scaffolding A-kinase anchoring protein (AKAP) and forms functional complexes with the related TRPV1 channel. This perspective will contextualize the recent biochemical and functional studies with emerging structural data with the aim of enabling a more thorough interpretation of the results, which may ultimately help to understand the roles of TRPA1 under various physiological and pathophysiological pain conditions. We demonstrate that an alteration to the putative lipid-binding site containing a residue polymorphism associated with human asthma affects the cold sensitivity of TRPA1. Moreover, we present evidence that TRPA1 can interact with AKAP to prime the channel for opening. The structural bases underlying these interactions remain unclear and are definitely worth the attention of future studies.

• Klíčová slova
• A-kinase anchoring protein, TRP channel, TRPA1, calmodulin, transient receptor potential,
• Publikační typ
• časopisecké články MeSH

The transient receptor potential channel A1 (TRPA1) is unique among ion channels of higher vertebrates in that it harbors a large ankyrin repeat domain. The TRPA1 channel is expressed in the inner ear and in nociceptive neurons. It is involved in hearing as well as in the perception of pungent and irritant chemicals. The ankyrin repeat domain has special mechanical properties, which allows it to function as a soft spring that can be extended over a large range while maintaining structural integrity. A calcium-binding site has been experimentally identified within the ankyrin repeats. We built a model of the N-terminal 17 ankyrin repeat structure, including the calcium-binding EF-hand. In our simulations we find the calcium-bound state to be rigid as compared to the calcium-free state. While the end-to-end distance can change by almost 50% in the apo form, these fluctuations are strongly reduced by calcium binding. This increase in stiffness that constraints the end-to-end distance in the holo form is predicted to affect the force acting on the gate of the TRPA1 channel, thereby changing its open probability. Simulations of the transmembrane domain of TRPA1 show that residue N855, which has been associated with familial episodic pain syndrome, forms a strong link between the S4-S5 connecting helix and S1, thereby creating a direct force link between the N-terminus and the gate. The N855S mutation weakens this interaction, thereby reducing the communication between the N-terminus and the transmembrane part of TRPA1.

• MeSH
• ankyrinová repetice fyziologie   MeSH
• kationtové kanály TRP chemie   fyziologie   MeSH
• kationtový kanál TRPA1 MeSH
• lidé MeSH
• molekulární modely MeSH
• motivy EF-ruky fyziologie   MeSH
• proteiny nervové tkáně chemie   fyziologie   MeSH
• simulace molekulární dynamiky MeSH
• vápník metabolismus   MeSH
• vápníkové kanály chemie   fyziologie   MeSH
• vazebná místa MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• kationtové kanály TRP MeSH
• kationtový kanál TRPA1 MeSH
• proteiny nervové tkáně MeSH
• TRPA1 protein, human MeSH Prohlížeč
• vápník MeSH
• vápníkové kanály MeSH

The transient receptor potential ankyrin 1 (TRPA1) channel is a Ca(2+)-permeable cation channel whose activation results from a complex synergy between distinct activation sites, one of which is especially important for determining its sensitivity to chemical, voltage and cold stimuli. From the cytoplasmic side, TRPA1 is critically regulated by Ca(2+) ions, and this mechanism represents a self-modulating feedback loop that first augments and then inhibits the initial activation. We investigated the contribution of the cluster of acidic residues in the distal C terminus of TRPA1 in these processes using mutagenesis, whole cell electrophysiology, and molecular dynamics simulations and found that the neutralization of four conserved residues, namely Glu(1077) and Asp(1080)-Asp(1082) in human TRPA1, had strong effects on the Ca(2+)- and voltage-dependent potentiation and/or inactivation of agonist-induced responses. The surprising finding was that truncation of the C terminus by only 20 residues selectively slowed down the Ca(2+)-dependent inactivation 2.9-fold without affecting other functional parameters. Our findings identify the conserved acidic motif in the C terminus that is actively involved in TRPA1 regulation by Ca(2+).

• MeSH
• buněčné linie MeSH
• kationtové kanály TRP chemie   metabolismus   fyziologie   MeSH
• kationtový kanál TRPA1 MeSH
• lidé MeSH
• molekulární sekvence - údaje MeSH
• mutace MeSH
• proteiny nervové tkáně chemie   metabolismus   fyziologie   MeSH
• sekvence aminokyselin MeSH
• sekvenční homologie aminokyselin MeSH
• simulace molekulární dynamiky MeSH
• vápník metabolismus   MeSH
• vápníkové kanály chemie   metabolismus   fyziologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• kationtové kanály TRP MeSH
• kationtový kanál TRPA1 MeSH
• proteiny nervové tkáně MeSH
• TRPA1 protein, human MeSH Prohlížeč
• vápník MeSH
• vápníkové kanály MeSH

The ankyrin transient receptor potential channel TRPA1 is a non-selective cationic channel that is expressed by sensory neurons, where it can be activated by pungent chemicals, such as AITC (allyl isothiocyanate), cinnamon or allicin, by deep cooling (<18 °C) or highly depolarizing voltages (>+100 mV). From the cytoplasmic side, this channel can be regulated by negatively charged ligands such as phosphoinositides or inorganic polyphosphates, most likely through an interaction with as yet unidentified positively charged domain(s). In the present study, we mutated 27 basic residues along the C-terminal tail of TRPA1, trying to explore their role in AITC- and voltage-dependent gating. In the proximal part of the C-terminus, the function-affecting mutations were at Lys969, Arg975, Lys988 and Lys989. A second significant region was found in the predicted helix, centred around Lys1048 and Lys1052, in which single alanine mutations completely abolished AITC- and voltage-dependent activation. In the distal portion of the C-terminus, the charge neutralizations K1092A and R1099A reduced the AITC sensitivity, and, in the latter mutant, increased the voltage-induced steady-state responses. Taken together, our findings identify basic residues in the C-terminus that are strongly involved in TRPA1 voltage and chemical sensitivity, and some of them may represent possible interaction sites for negatively charged molecules that are generally considered to modulate TRPA1.

• MeSH
• aminokyseliny bazické genetika   fyziologie   MeSH
• ankyrinová repetice MeSH
• ankyriny MeSH
• ionty farmakologie   MeSH
• kationtové kanály TRP chemie   metabolismus   MeSH
• kationtový kanál TRPA1 MeSH
• lidé MeSH
• membránové potenciály fyziologie   MeSH
• nervové receptory chemie   MeSH
• proteiny nervové tkáně chemie   metabolismus   MeSH
• statická elektřina MeSH
• substituce aminokyselin MeSH
• vápníkové kanály chemie   metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• aminokyseliny bazické MeSH
• ankyriny MeSH
• ionty MeSH
• kationtové kanály TRP MeSH
• kationtový kanál TRPA1 MeSH
• proteiny nervové tkáně MeSH
• TRPA1 protein, human MeSH Prohlížeč
• vápníkové kanály MeSH