National Doctoral Programme in
Informational and Structural Biology

Our goal is to understand the structural basis for the function of a variety of different molecules, focussing on the chemistry of soluble enzymes and the biochemistry of membrane and membrane-associated proteins. To this end, we produce and purify the proteins for study by x-ray crystallography, molecular modelling and structural analysis. The proteins currently studied include inorganic pyrophosphatases, muconate lactonising enzymes, pyruvate formate lyase, human a2B-adrenergic receptor, GDNF receptor a, as well as the adhesion proteins a-agglutinin, YadA and GafD.

Soluble inorganic pyrophosphatases (PPases) are ubiquitous and essential, which performs a simple reaction that requires divalent cation. As we have solved the structure (among others) of yeast PPase to very high resolution, we are using the system to probe enzyme function at the quantum mechanical level. We have also solved the structure of S. mutans PPase, the first member of a relatively-rare but nonetheless widespread second family of PPases. These are completely unrelated to family I PPases in structure but have a very similar active site and, we therefore propose, mechanism.

Muconate lactonising enzyme (MLE) and carboxyMLE (CMLE) are part of the b-ketoadipate pathway, by which certain aromatic compounds are converted into Krebs cycle intermediates. Organisms with these pathways recycle lignin, the second most common material in the biomass, in the Carbon cycle. We have solved the structure of a bacterial MLE and a fungal CMLE, which again have completely unrelated structures. There are, however, intriguing points of mechanistic similarity between the two enzymes.

Pyruvate formate lyase (PFL) from E. coli is central to bacterial anaerobic synthesis. We have solved its structure and have shown that it is structurally-related to the ribonucleotide reductases. Our structural data supports the proposed reaction mechanism where Cys418 transfers the acetyl moiety to CoA while Cys419 is involved in the fascinating radical mechanism.

a2-Adrenergic receptors (a2-AR) belong to the G-protein coupled receptor superfamily (GPCR). These are integral membrane proteins which transduce a wide variety of signals. Activation of the different a2-AR subtypes causes different, even opposing, effects; many of these effects are clinically important including anaesthesia and reduction in hypertension. Consequently, subtype-specific drugs would be highly important. We therefore aim to elucidate the structure of a2B-adrenergic receptor, as this will provide the best platform for subtype-specific drug design.