Biology subjects

Contreras, G. F.

Publications and source records attributed to Contreras, G. F..

3 recordsLinked to original sources

bioRxiv2025

The BK channel-NS1619 agonist complex reveals molecular insights on allosteric activation gating

BK channels play essential roles in a wealth of physiological functions, including regulating smooth muscle tone and neurotransmitter release. Its dysfunction, often caused by loss-of-function mutations, can lead to severe phenotypes, including ataxia and sensory impairment. Despite the therapeutic potential of BK channel agonists, the molecular mechanisms by which they stabilize the pores open conformation remain unclear. Using cryo-electron microscopy and molecular dynamic simulations, we identified that NS1619, a synthetic benzimidazolone agonist, first described as a BK opener, binds within a pocket formed by the S6/RCK1 linker and the S4 transmembrane segment. Agonist binding drives a twisting motion in the S6 segment, enabling critical interactions with residues K330, K331, and F223. Our findings clarify the mechanism of NS1619 and suggest that its binding site can accommodate other agonists, highlighting a promising target for therapeutic development. TeaserBK channel activation by NS1619 reveals key binding interactions, offering insights for designing targeted therapeutic agents.

biophysics↗

bioRxiv2023

Structural Basis of Voltage-Dependent Gating in BK Channels and Its Coupling to the Calcium Sensor

The allosteric communication between pore domain, voltage sensors, and Ca2+ binding sites in the Ca2+-activated K+ channel (BK) shapes its multiple physiological roles as the preeminent signal integrator in excitable systems. BK displays shallow voltage sensitivity with very fast gating charge kinetics, yet little is known about the molecular underpinnings of this distinctive behavior. Here, we explore the mechanistic basis of coupling between voltage-sensing domains (VSDs) and calcium sensors in Aplysia BK by locking the VSDs in their resting (R196Q and R199Q) and activated (R202Q) states, with or without calcium. Cryo-EM structures of these mutants reveal unique tilts at the S4 C-terminal end, together with large side-chain rotameric excursions of the gating charges. Importantly, the VSD resting structure (R202Q) also revealed BK in its elusive fully closed state, highlighting the reciprocal relation between calcium and voltage sensors. These structures provide a plausible mechanism where voltage and Ca2+ binding converge physically and couple energetically to define the conformation of the pore domain and thus, BK full functional range.

biophysics↗

bioRxiv2021

Cryo-EM Structures of Prestin and the Molecular Basis of Outer Hair Cell Electromotility

The voltage-dependent motor protein, Prestin (SLC26A5) is responsible for the electromotive behavior of outer hair cells (OHCs). Here, we determined the structure of dolphin Prestin in six distinct states using single particle cryo-electron microscopy. Structural and functional data suggest that Prestin adopts a unique and complex set of states, tunable by the identity of bound anions. Complexes with the inhibitor salicylate show that it competes for the anion-binding site of Prestin. These conformations reveal a novel mechanism of area expansion that depends on the helix flexibility and conformational transitions at the membrane protein interface and putatively affects the physical state of the surrounding membrane. These observations illuminate the structural basis of Prestin electromotility, a key component of the mammalian cochlear amplifier.

neuroscience↗