PUBLICATION
The role of the ectodomain serine 275 in shaping the binding pocket of ATP-gated P2X3 receptor
- Authors
- Petrenko, N., Khafizov, K., Tvrdonova, V., Skorinkin, A., and Giniatullin, R.
- ID
- ZDB-PUB-110907-6
- Date
- 2011
- Source
- Biochemistry 50(39): 8427-36 (Journal)
- Registered Authors
- Keywords
- none
- MeSH Terms
-
- Adenosine Triphosphate/pharmacology
- Amino Acid Sequence
- Animals
- Binding Sites
- Calcium/pharmacology
- Computer Simulation
- Kinetics
- Models, Molecular
- Purinergic P2 Receptor Agonists/metabolism
- Rats
- Receptors, Purinergic P2X3/chemistry*
- Receptors, Purinergic P2X3/drug effects
- Receptors, Purinergic P2X3/genetics
- Receptors, Purinergic P2X3/metabolism
- Serine/genetics
- Serine/physiology*
- PubMed
- 21879712 Full text @ Biochemistry
Citation
Petrenko, N., Khafizov, K., Tvrdonova, V., Skorinkin, A., and Giniatullin, R. (2011) The role of the ectodomain serine 275 in shaping the binding pocket of ATP-gated P2X3 receptor. Biochemistry. 50(39):8427-36.
Abstract
TP-activated P2X3 receptors expressed in nociceptive sensory neurons play an important role in pain signalling. Basic properties of this receptor subtype, including very strong desensitization, depend on the rate of agonist dissociation from the binding site. Even though the rough structure of the ATP binding site has been proposed based on the X-ray structure of zebrafish P2X4 receptor and mutagenesis studies, the fine subunit-specific structural properties predisposing to tight capture of the agonist inside the binding pocket have not been elucidated yet. In the current work, by exploring in silico the functional role for the left-flipper located in the ectodomain region, we identified within this loop a candidate residue S275, which could contribute to the closure of the agonist-binding pocket. Testing of the S275 mutants using the patch-clamp technique revealed a crucial role of the S275 in agonist binding and receptor desensitization. The mutant S275A showed reduced onset of desensitization, accelerated resensitization and was weakly inhibited by nanomolar agonist. Extracellular calcium application produced inhibition instead of facilitation of membrane currents. Moreover, some full agonists became only partial agonists when applied to the S275A receptor. These effects were stronger with the more hydrophobic mutants S275C or S275V. Taken together, our data suggest that S275 contributes to the closure of the agonist-binding pocket and that effective capture of the agonist provided by the left-flipper in calcium-dependent manner determines the high rate of desensitization, slow recovery, and sensitivity to nanomolar agonist of the P2X3 receptor.
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