Dr. Cheng’s Research

The Structural Basis of Neurosteroid Binding to the GABA(A) Receptor

Neurosteroids are endogenous brain sterols that potently modulate GABA(A) receptors (GABAARs), and are being developed as anesthetics or treatments of neurologic and psychiatric disorders. Although neurosteroid modulation of the GABAAR has been well characterized, neurosteroid binding to the GABAAR is not well understood. A detailed understanding of the stoichiometry/site(s), orientation and pharmacology of neurosteroid binding to the GABAAR is essential for structure-based design of neurosteroid anesthetics. To address this deficiency, the candidate will apply photo-affinity labeling with an existing library of neurosteroid photolabeling reagents, and top-down mass spectrometry (MS), a technique that analyzes intact membrane proteins, to characterize neurosteroid photolabeling of the GABAAR. Aim 1 is to determine the stoichiometry/site(s) and orientation of neurosteroid photolabeling of ELIC-GABAAR chimeras (tractable model proteins where the transmembrane domain consists of GABAAR subunits), and aim 2 is to determine the stereoselectivity of neurosteroid photolabeling. This work will yield novel insights into the structural basis of neurosteroid binding to the GABAAR. It will also establish a generalizable method using top-down MS for characterizing small molecule photolabeling of membrane proteins, and is anticipated to lead to sustainable R01-level funding. This research will be conducted under the mentorship of Dr. Alex Evers, an expert in anesthetic pharmacology, photo-affinity labeling and mass spectrometry analysis of membrane proteins. The candidate will also be working closely with Dr. Michael Gross, a leader in top-down MS of membrane proteins at Washington University. The Anesthesiology Department at Washington University provides a robust environment for research in molecular pharmacology.