posted on 2018-05-29, 08:44authored byFedir M. Bokhovchuk, Neil Bate, Nadezda V. Kovalevskaya, Benjamin T. Goult, Chris A. E. M. Spronk, Geerten W. Vuister
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 ].
Funding
G.W.V. acknowledges funding during various stages of this project by the Dutch Organization of Scientific Research (NWO; 700.55.443 and 700.57.101), BBSRC (BB/J007897/1), and MRC (MR/L000555/1 and MR/P00038X/1).
History
Citation
Biochemistry, 2018, 57 (18), pp. 2623-2635
Author affiliation
/Organisation/COLLEGE OF LIFE SCIENCES/Biological Sciences/Molecular & Cell Biology
Accession Codes
Chemical shifts and restraints were submitted to the BMRB (accession number 34161), and the ensemble of 20 conformers were submitted to the wwPDB (accession number 5OEO).;The file associated with this record is under embargo until 12 months after publication, in accordance with the publisher's self-archiving policy. The full text may be available through the publisher links provided above.