Structural basis and energy landscape for the Ca2+gating and calmodulation of the Kv7.2 K+channel.Bernardo-Seisdedos, G., Nunez, E., Gomis, C., Malo, C., Villarroel, A., Millet, O.
(2018) Proc Natl Acad Sci U S A 115: 2395-2400
- PubMed: 29463698
- DOI: https://doi.org/10.1073/pnas.1800235115
- Primary Citation of Related Structures:
- PubMed Abstract:
The Kv7.2 (KCNQ2) channel is the principal molecular component of the slow voltage-gated, noninactivating K + M-current, a key controller of neuronal excitability. To investigate the calmodulin (CaM)-mediated Ca 2+ gating of the channel, we used NMR spectroscopy to structurally and dynamically describe the association of helices h A and h B of Kv7.2 with CaM, as a function of Ca 2+ concentration. The structures of the CaM/Kv7.2-hAB complex at two different calcification states are reported here. In the presence of a basal cytosolic Ca 2+ concentration (10-100 nM), only the N-lobe of CaM is Ca 2+ -loaded and the complex (representative of the open channel) exhibits collective dynamics on the millisecond time scale toward a low-populated excited state (1.5%) that corresponds to the inactive state of the channel. In response to a chemical or electrical signal, intracellular Ca 2+ levels rise up to 1-10 μM, triggering Ca 2+ association with the C-lobe. The associated conformational rearrangement is the key biological signal that shifts populations to the closed/inactive channel. This reorientation affects the C-lobe of CaM and both helices in Kv7.2, allosterically transducing the information from the Ca 2+ -binding site to the transmembrane region of the channel.
Instituto Biofisika (Consejo Superior de Investigaciones Científicas, Universidad del País Vasco), University of Basque Country, 48940 Leioa, Spain firstname.lastname@example.org email@example.com.