Section of Structural Biology
Chairman: Professor David Barford FRS
Scientific Overview
Our work is focused on structural and biochemical studies of proteins and complexes of importance in the aetiology and treatment of cancer. Our research activities utilise the methodologies of X-ray crystallography, electron microscopy and a variety of biochemical and biophysical techniques, and can be subdivided into the following biological areas:
- DNA damage recognition, signalling and repair
- Signal transduction processes
- Mechanisms and consequences of protein phosphorylation and protein ubiquitination
- Transcriptional regulation
- Chaperone-mediated protein activation
- Cell cycle control
- Chromatin remodelling
- Proteasome structure
- Inositol tris-phosphate receptor structure
- Structure-based drug design
Virtually every cellular function is regulated by post-translational modifications such as reversible protein phosphorylation, acetylation and ubiquitin-dependent events. Such processes regulate the activities of signal transduction cascades that ultimately lead to changes in gene expression and control of the cell cycle and apoptosis. Dysregulation of these pathways has important implications for the development of cancer. Our interests are concerned with understanding the structural mechanisms by which the post-translational modification of proteins regulates signal transduction pathways and the cell cycle. Professor David Barford’s laboratory investigates the structures and mechanisms of protein kinases, phosphatases and E3 ubiquitin ligases to understand these proteins at a fundamental level, and also to facilitate rational drug design programmes.
In the cell cycle field a major interest is focussed on understanding the molecular mechanism and architecture of the anaphase promoting complex, a large multi-subunit E3 protein ubiquitin ligase that functions to regulate cell cycle transitions by targeting key cell cycle proteins, such as cyclin and securin for degradation by the ubiquitin proteasome system.
Our interest in RNA interference is focussed on understanding the molecular mechanisms whereby small interfering RNAs repress expression of specific genes. Structural insights into this process could lead to design of more effective siRNAs both as a tool for understanding cellular signalling, and as a therapeutic agent for treating cancer.
To understand the mechanism of RAS post-translational modifications, necessary for the signalling function of RAS, we have initiated a programme to determine the crystal structures of the RAS converting enzyme (RCE1), a CAAX motif protease, and isoprenyl cysteine methyl transferase (ICMT), a cysteinyl methyltransferase.
The Peal Group operates in three main biological areas: DNA repair, Signal Transduction and Transcriptional Regulation, and Chaperone Mediated Protein Activation. In all our studies we are seeking to obtain insights into the structural basis for the biological phenomena and understand the specificity of the macromolecular interactions involved, with the aim of using this knowledge to assist the development of new, target-directed anticancer therapies.
In the DNA repair field, we are studying the structure function and regulation of multi-protein complexes involved in the recognition and coordinated repair of aberrant bases, single-strand gaps and double-strand breaks. We are also studying the signalling pathways that report the presence of DNA damage to the cell cycle regulatory apparatus, and promote cell cycle arrest to allow completion of DNA repair.
Our studies of signal transduction and transcriptional regulation are focused on scaffold-mediated protein kinase specificity, particularly in the carcinogenic Wnt signalling pathway, and on the regulation of gene expression by co-repressors such as Gro/TLE, and by effectors such as p300/CBP and CARM-1 that covalently modify chromatin.
Our molecular chaperone studies are primarily directed at understanding the structure and mechanism of Hsp90, which is the central player in a dynamic series of multi-protein complexes with key roles in activation, regulation and targeted destruction of important cell regulatory pathways that are frequently misregulated in cancer. We are engaged in structural and functional studies of a variety of Hsp90 complexes with co-chaperones and client proteins.
The research of Dr Richard Bayliss is in the field of mitotic regulation is focussed on the regulation of mitotic spindle assembly by the serine/threonine kinase Aurora-A. Aurora-A is overexpressed in many human cancers, including in the majority of breast cancers and is thus a promising drug target to combat cancer. Several first-generation Aurora inhibitors have been synthesised that establish the principle of Aurora inhibition in vivo, but that cannot discriminate between the three members of the Aurora family. In collaboration with Dr Spiros Linardopoulos (Breakthrough Breast Cancer and Cancer Therapeutics), Dr Bayliss’ team is working towards making inhibitors specific for Aurora-A. Other work in the team focuses on the regulation of Aurora-A by phosphorylation, ubquititylation and protein-protein interactions.
In Dr Jon Wilson’s studies in chromatin regulation his team aims to understand the mechanisms by which changes in the structural organisation of DNA packaging are used to regulate processes such as transcription and DNA repair. One aspect of this is the context specific post-translational modification of histone proteins which is proposed to form an ‘epigenetic’ code that through the recruitment of replication, repair and transcriptional complexes determines patterns of gene expression and directs the response to DNA damage. His group are using biochemistry and structural biology techniques to understand the function and regulation of the enzymes responsible for the addition of these marks and recognition of modified histones. Currently we are focusing on issues concerning the specificity of methyltransferase enzymes. In addition to addressing general questions regarding basic biology the hope is to assess the validity of such enzymes as potential drug targets.
Dr Ed Morris applies the techniques of electron microscopy and single particle reconstruction techniques to understand the structure and function of large proteins of medical and scientific interest. Current focus includes the proteasome, the inositil 1,4,5 tris-phosphate receptor and the signalosome.
Recent Highlights
- We were delighted to welcome three new teams recruited to the Section that greatly contribute to our scientific activities. These three groups are: Dr Richard Bayliss (mitotic regulation and cancer), Dr Ed Morris (structural electron microscopy) and Dr Jon Wilson (chromatin regulation). Ed Morris heads our newly installed electron microscopy facility managed by Dr Fabienne Beuron
- Completion of the electron microscopy suite and installation and commissioning of the new Tecnai T12 and Tecnai F20 electron microscopes
- We determined the molecular mechanism of AKAP specificity for PKA regulatory subunits
- Determination of the structure of CYLD, a deubiquitinating enzyme tumour suppressor protein whose inactivation by mutation results in familial cylindromatosis, a genetic disposition to multiple skin tumours affecting the head and neck
- Determination of the structure of the chaperone associated E3-ubiquitin ligase CHIP and its complex with the Ubc13-Uev1a E2 ubiquitin conjugating enzyme, revealing the basis for CHIPs recruitment to Hsp90 and its ability to interact with specific E2s
- Structure determination and genetic analysis of the C-terminal region of the transcriptional co-repressor Gro/TLE, in complex with WRPW and eh1 targeting motifs, revealing the structural basis for recruitment of Gro/TLE to different transcription factor families
- Assembly and single particle electron microscopy 3D reconstruction of the DNA-PK holoenzyme (DNA-PKcs – Ku88 – Ku70) bound to DNA, revealing the location of the Ku heterodimer in the holoenzyme complex, and suggesting a model for synaptic interaction
- Structure determination of the catalytic region of the DNA damage signalling protein kinase CHK2, revealing how CHK2 is activated by dimerisation following upstream detection of DNA damage
- Determination of the crystal structure of the Hsp90 molecular chaperone in the closed state, in complex with an ATP-analogue and the co-chaperone P23/Sba1. This landmark study is the culmination of 10 years’ biochemical and structural work in the laboratory, and provides a clear understanding of the role of ATP in Hsp90s chaperone mechanism, and how HSp90-tergetted anti-tumour agents
- Determination of the architecture of an Hsp90-Cdc37-Cdk4 complex by single-particle electron microscopy. This study provides the first view of how a client protein interacts with the Hsp90 machinery
