The Structural Basis of Calcium-Dependent Inactivation of the Transient Receptor Potential Vanilloid 5 Channel.Bokhovchuk, F.M., Bate, N., Kovalevskaya, N.V., Goult, B.T., Spronk, C.A.E.M., Vuister, G.W.
(2018) Biochemistry 57: 2623-2635
- PubMed: 29584409
- DOI: 10.1021/acs.biochem.7b01287
- PubMed Abstract:
The transient receptor potential vanilloid channel subfamily member 5 (TRPV5) is a highly selective calcium ion channel predominately expressed in the kidney epithelium that plays an essential role in calcium reabsorption from renal infiltrate. In or ...
The transient receptor potential vanilloid channel subfamily member 5 (TRPV5) is a highly selective calcium ion channel predominately expressed in the kidney epithelium that plays an essential role in calcium reabsorption from renal infiltrate. In order to maintain Ca 2+ homeostasis, TRPV5 possesses a tightly regulated negative feedback mechanism, where the ubiquitous Ca 2+ binding protein calmodulin (CaM) directly binds to the intracellular TRPV5 C-terminus, thus regulating TRPV5. Here we report on the characterization of the TRPV5 C-terminal CaM binding site and its interaction with CaM at an atomistic level. We have solved the de novo solution structure of the TRPV5 C-terminus in complex with a CaM mutant, creating conditions that mimic the cellular basal Ca 2+ state. We demonstrate that under these conditions the TRPV5 C-terminus is exclusively bound to the CaM C-lobe only, while it confers conformational freedom to the CaM N-lobe. We also show that at elevated calcium levels, additional interactions between the TRPV5 C-terminus and CaM N-lobe occur, resulting in formation of a tight 1:1 complex, effectively making the N-lobe the calcium sensor. Together, these data are consistent with and support the novel model for Ca 2+ /CaM-dependent inactivation of TRPV channels as proposed by Bate and co-workers [ Bate , N. , et al. ( 2018 ) Biochemistry , ( 57), DOI: 10.1021/acs.biochem.7b01286 ].
JSC Spronk , Vilnius , Lithuania.,Department of Molecular and Cell Biology, Leicester Institute of Structural and Chemical Biology , University of Leicester , Lancaster Road , Leicester LE1 9HN , United Kingdom.