Voltage-gated sodium channels (Navs) are responsible for the initiation and propagation of action potentials in excitable organs such as the heart, the brain and the skeletal muscles. Dysregulation or malfunction of these proteins cause serious diseases affecting the heart, the brain and the skeletal muscles. A better understanding of the molecular mechanisms underlying Nav function and modulation is essential to develop efficient drugs against these pathologies. Bacterial Navs (BacNavs) have been premier, tractable systems for understanding fundamental aspects of eukaryotic Nav function and modulation.The purpose of this Research Plan is to study both the functional and structural properties of BacNavs use-dependent modulation by pore activators and pore blockers, using batrachotoxin (BTX) and BTX enantiomer (ent-BTX) as model compounds. This project will be using a combination of electrophysiology (patch clamp) and structural biology (X-ray crystallography) approaches to achieve the following aims: Aim 1: Identification and biophysical characterization of pore residues involved in channel modulation by BTX and ent-BTXAim 2: Determination of Nav ' BTX and Nav ' ent-BTX complex X-ray structuresWe have engineered a BacNav mutant that can be activated by BTX and blocked ent-BTX in a similar way as the Navs. We have initiated efforts to co-crystallize BacNav-protein complexes using this BacNav mutant. The identification of BacNav pore residues involved in channel modulation by BTX and ent-BTX, and the X-ray crystal structure determination of BacNavs in complex with these unique chemical agents will deliver a detailed molecular view of toxin-Nav interactions, which will considerably increase our understanding of the influence of ligand binding on channel conformational changes, and shed light on the molecular mechanisms underlying use-dependent Nav modulation by pore-activators and pore blockers. Such findings will ultimately empower the rationale design of small molecules for modulating Nav function. Design of such agents will enable 'fine-tuning' of Nav activity and should have clinical value for the treatment of chronic Nav-related diseases such as cardiac arrhythmia, epilepsy, chronic pain and periodic paralysis.
|Program type||Postdoctoral Fellowship|
|Effective start/end date||01/01/2019 → 12/31/2020|