Molecular Basis of Alcohol's Action

A major part of the research in our lab is focussed on understanding the molecular mechanisms of alcohol's actions that lead to alcohol intoxication and alcohol dependency. Over the last decade there has been tremendous progress in defining the moelcular targets of alcohol and it has been shown that alcohol can bind directly to a number of different proteins, including ion-channels, kinases and scaffolding proteins. Binding of alcohol leads to changes in enzyme activity, sub-cellular localization or signal transduction. Even more exiting, it has been shown that single point mutations in ligand gated ion-channels such as the GABA-A and Glycine receptors can completely remove the alcohol sensitvity of these receptors. There is now strong evidence that many of the effects of alcohol are associated with a direct interaction between alcohol and the protein. Our goal is to use structural and biophysial methods to understand how binding of alcohol to these protein can produce changes in the protein function

We are using structural biology and biophysical methods to probe the molecular events involved in alcohol binding. In particular we use Nuclear Magnetic Resonance (NMR) spectroscopy and X-ray crystallography to investigate the binding of alcohol to proteins. Proteins currently being studied in the lab include model aclohol binding proteins (see below) and ion-channels and kinases that have been shown to be particularly sensitive to alcohol. Our approach is to use structural biology approaches to identify the key interactions in the alcohol-binding site. Then using molecular biology methods, in combination with fluorescence and calorimetry, we make point mutations to residues in the binding site to probe the relative contributions that these residues make to alcohol binding. From this, we have developed a working hyptoesis about what factors define an alcohol binding site, and this will help us to understand the nature of alcohol binding sites and guide us in our efforts to develop new apporahes to treat alcohol dependency.

This work is supported by NIH National Institute of Alcoholism and Alcohol Abuse (NIAAA)

Left: Part of electron density map of Lush solved at 1.25 Angstrom resolution (Click for larger version Right: Structure of the Ethanol binding pocket in the Drosophila odorant binding protein, Lush. Ethanol binds into a hydrophobic pocket and makes hydrogen bond contacts to Ser52 and Thr57. These residues provide the scaffold of a high-affinity alcohol binding site.(Click for a larger version).

2. How do Insects Smell: From Pheromones to Foot Odors

The insect olfactory system is a highly organized and incredily sensitive chemosensory system that is capable of detecting chemical odors present in the air at concentrations of only a few parts per billion. The olfactory system controls the behavioral repsonse to food, mating and migration signals. A key component of this olfactory system is a family of odorant binding proteins which bind to the odorant molecule and form a complex which is capable of activating an odorant receptor. Chemosensory responses to a specific odor depend on both the identity of the specific odorant receptor and also to the odorant binding protein. As a result it may be possible to develop novel methods to interfere with a specific signaling pathway as mechanism of pest control.

We are interested in understanding how these proteins can be targetd as a mechanism to control the spread of malaria, dengue fever and west nile virus. To this end we are using NMR spectroscopy and X-ray crystallography to probe how OBPs from different insects interact with pheromones and other chemical stimulti that are commonly encountered within the environment. This builds on our work with the LUSH.

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