Allosteric GABA-A receptor modulation: computational and experimental model systems
Please notice these positions are no longer vacant.

Towards subtype selective modulators of GABAA receptors
It is commonly agreed that subtype selective modulators of GABAA receptors are potentially useful for therapy and research. Their development still is not possible by structure guided methods, as structures of ligand bound GABAA receptors that are sufficiently accurate are still lacking. Modulatory ligands of GABAA receptors cover an interesting spectrum of clinical action, including anxiolysis, sedation and anticonvulsive effects. The most extensively characterized site of such action is the benzodiazepine binding site in diazepam sensitive receptor subtypes (Sigel, 2002). Recent advances in our lab, computing 3D models of a diazepam-bound receptor state provide the basis for investigating structural conservation and deviation of other, similar binding sites such as the "diazepam-insensitive" α4/6 subtypes or the γ1-containing subtypes studied also by the groups of S. Hering by computational techniques and by studying mutated receptors.
Workplan: The PhD student will perform modelling and docking studies on a ligand bound model of an α1γ2 receptor. GABAA containing subtypes, and consider the effect of the different αn subunits. Development of subtype-selective drugs would be accelerated by such structural information. Predictions made by the computational models will be tested by binding experiments in wild type and mutated receptors.
Methods: The student will learn and apply the following techniques: Homology modelling, flexible docking and short MD simulations to generate structural models. Visualizing and interpreting ligand bound protein models. Mutagenesis, expression of recombinant protein in cell culture, radioligand binding assays will yield the data needed to confirm the predicted ligand-protein interactions.

Understanding subtype selective allosteric modulation of GABAA receptors
Currently the best-investigated benzodiazepine binding site is the α1γ2 subtype. In addition to many compounds that modulate GABA induced currents via this allosteric site with comparable potency and efficiciency, some compounds are noted for subtype preferences. In this study we aim to dissect the molecular basis for such action. We have a range of ligands that belong to the same chemical class, where different substituents elicit subtype specific responses. These are an ideally suited tool to investigate the interactions between ligand features and protein features that lead to subtype specificity. Mutated receptors will be generated on the basis of computational models. Changes of subtype specific modulatory action will be investigated in recombinantly expressed, mutated receptors by two electrode voltage clamp recordings in Xenopus laevis oocytes.

Workplan: The PhD student will use computational models to derive hypotheses about mechanisms that lead to subtype selectivity. Based on these, supposed gain- and loss- of function constructs will be designed, made and their pharmacology investigated with binding assays and functional studies using electrophysiology. The functional data will in turn be used to verify, improve or revise the hypotheses.
Methods: The student will learn and apply the following techniques: Visualizing and interpreting ligand bound protein model structures. Mutagenesis, expression of recombinant protein in cell culture, radioligand binding assays. Two electrode voltage clamp electrophysiology.