The Centre brings together a large group of structural molecular biologists, chemists and physicists
working on the structure and function of a wide range of biological molecules,
biomolecular assemblies and complexes. It specialises in all the current major
techniques for high-resolution structure determination of large molecules, including
X-ray crystallography, NMR
spectroscopy, and electron microscopy
as well as a battery of sophisticated biophysical tools such as mass
spectrometry, surface plasmon resonance
and time-resolved spectroscopies. These
techniques are complemented by theoretical approaches such as molecular
modelling and bioinformatics.
Structural studies, however, are not taken in isolation, and the mission of
the Centre is to integrate these with powerful programmes of functional analysis,
since the ultimate goal of biology is to understand the function of biological
systems rather than just their structure. The enormous success and potential
of genome projects is generating a flood of information on protein sequences
and the challenge for the Centre over the coming years is to assign structure
and function to the products of the genes that have been sequenced.
The current research priorities of the Centre are divided into five major themes:
Protein-DNA/RNA Interactions underpin the fundamental processes by which the
genetic information in DNA and RNA is controlled. Studies of protein-DNA complexes include
intermediates in genetic recombination where resolvases bind to four-way DNA Holliday
junctions to cleave them back to duplexes, DNA polymerases (especially as potential drug
targets), transcriptional repressors and activators, restriction endonucleases, helicases,
repair enzymes and plasmid replication initiator proteins. Studies on protein-RNA
complexes exploit particular expertise in RNA synthesis technology, and include novel
approaches such as a phage capsid supramolecular support system for RNA structure
determination by crystallography in the absence of RNA crystals. Major interests also
centre around RNA structures in pathogenic RNA viruses that may allow new routes to
therapies in the future.
Membrane Proteins constitute a huge class of critically
important molecules, especially in higher organisms. Their genes occupy as much as a third of the genome, and they also constitute
the majority of known drug targets. The Centre has a major programme of structural and functional studies on several classes of
membrane proteins, including membrane transporters and ion channels. Prokaryotic and eukaryotic membrane transporters, that
translocate sugars, nucleotides, antibiotics or other solutes across membranes form a particular focus. The Centre is also a
key component of the "Membrane Protein Structure Initiative" (Mpsi), a major BBSRC-funded UK consortium applying high-throughput,
automated structural genomics methods to determine crystal structures of membrane proteins.
Protein Folding and Assembly have assumed particular importance with the
relatively recent recognition that a number of serious diseases (such as CJD, BSE,
Alzheimer's and haemodialysis-related amyloidosis) result from folding disorders.
There is a vigorous programme studying the molecular mechanisms of protein folding, both
for proteins with simple folds, such as helical bundles and beta meanders, and more
complex topologies such as Greek key domains, together with a project on the molecular
chaperone GroEL. The structures of intermediates in the folding pathways are investigated
using NMR, stopped-flow fluorescence and circular dichroism (CD), protein engineering and
hydrogen-exchange using electrospray mass spectrometry (ESMS). Highlights include the
dissection of the folding pathway for pseuodoazurin and CD2, as well as detection of
different folding mechanisms for bacterial immunity proteins. Recent innovations are the
construction of temperature-jump apparatus capable of monitoring folding transitions in
nanoseconds and of a mechanical device for unfolding single protein molecules (see Methods
Development). Direct studies of folding of proteins responsible for folding diseases such
haemodialysis-related amyloidosis and Alzheimer's are also underway.
Molecular Recognition and Catalysis covers a wide range of studies of enzyme
mechanism and specific recognition between molecules. Several medically important enzymes
are being studied structurally as potential drug targets, such as angiotensin-converting
enzyme and other membrane-bound peptidases, bacterial cell wall synthesising enzymes and
the human clotting factor XIII. A comprehensive programme on the structure and mechanism
of copper-containing galactose and amine oxidases is aimed at elucidating the chemistry of
the catalytic pathway in atomic detail, by determining the structures of all the reaction
intermediates using novel anaerobic and cryogenic trapping techniques. A programme of
enzyme design is aimed at engineering aldolases to produce novel enzyme catalysts for
stereospecific carbon-carbon bond formation. Recognition studies mainly centre around
protein-carbohydrate complexes that are critically important for infectious diseases where
micro-organisms use them as a route for initial infection or as targets for toxins.
Methods Development in the centre covers a number of areas. Protein single
molecule mechanics is a major new area and covers both studies on muscle mechanism and
protein unfolding. Methods are available to unfold single protein molecules while
measuring both he necessary force and the associated spectroscopic changes. Major advances
in single-particle EM image processing are being made in many laboratories and the Centre
has a programme to extend this to transient molecular conformations and complexes by a
spray-mixing method allowing millisecond time resolution. Developments in NMR include new
methods for analysing oligosaccharide complexes and protein folding intermediates.
Bioinformatics programmes are aimed at automatic ligand design to generate new
pharmaceuticals and new methods for analysing genome sequence information in terms of the
predicted structure and function of the encoded proteins.