Dr Pierre Rizkallah - Research Interests

Immune System Proteins:

TCR MHC interaction

This work is in collaboration with Jonathan Boulter (Avidex & Cardiff) and George Gao (Oxford). Various wild type and mutant T-cell Receptors, Human Leukocyte Antigen and co-receptors (CD8), are being studied as individual molecules or in complex. The aim of the research is to pinpoint the determinants of specificity and affinity in these proteins, in order to engineer mutants with desired properties.

PDB Entries: 2PYF, 2PYE, 2P5W, 2P5E, 2HP4, 2F53, 2F54, 2BCK, 2BNR, 2BNQ, 2BNU

Human Ryanodine Receptor, RyR2:

ATP Binder

RyR2 is a membrane associated protein in the heart muscle sarcoplasm. It functions as a Ca2+ channel, controlling the Ca2+ flux underlying the heart beat. Mutations in various parts of the molecule have been associated with disease. As this molecule is very large, it is being studied in smaller domains that are functional. Each is being expressed separately, will be crystallised and its structure solved in due course.




Previous Research Activities

Crustacyanin Research:

Alpha Crust

Crystals of the camouflage protein Crustacyanin were available since the early 1980's, with no structure solution. In this work, the novel approach of infusing pressurised Xe into the crystals was used, and data were collected with X-rays at 2.0Å wavelength. The anomalous signal of Xe and S was used to solve that sub-structure, which eventually yielded the complete structure. The project is in collaboration with John Helliwell (Manchester), Peter Zagalsky (Royal Holloway College) and Naomi Chayen (Imperial College).

PDB Entries: 1GKA, 1H91, 1S2P, 1S44

Lectin Research:

SCA NPL

Work on the daffodil lectin has yielded the structure of its complex with mannobiose, refined at 2.0Å resolution. This project is based at Daresbury Laboratory. Mannose-specific lectins from the bulbs of Amaryllis and Bluebell were isolated and crystallised with and without ligands. Seven structures in all were solved and refined. A number of publications have appeared and some more are in preparation. This work is in collaboration with Prof. Colin D. Reynolds, Liverpool John Moores University. The Lentil lectin was crystallised in the unbound form in two space groups, and in complex with Sucrose. All three types of crystals diffracted to 1.5Å resolution or higher. Refinement is now complete, and manuscripts are being prepared. This work is in collaboration with Colin D. Reynolds (Liverpool John Moores University).

PDB Entries: 1B2P, 1DLP, 1NPL

Porin Research:

Porin

This research started in collaboration with Dr Richard Pauptit (Basel), and continued with Tilman Schirmer (Basel). Early work on the matrix Porin with the FAST detector was aimed at methodology development. The structure was also studied in a different space group. Maltoporin complexes with a series of saccharides of different lengths were studied to determine the mode of transport of the substrate across the bacterial membrane. The related mannose transporter system, permease II, domain A, and a Se-Met mutant, were used to solve the structure at 1.7Å resolution. Domain B crystallographic data were collected of the native and heavy atom derivatives. The structure was solved at 2.9Å resolution.

PDB Entries: 1AF6, 1MPM, 1MPN, 1MPO, 1MPQ, 1OPF

Snake Venom Proteins:

Cvant

This investigation was in collaboration with David Theakston (Liverpool School of Tropical Medicine). It aimed at the characterisation of the haemorrhagin from the venom of the Kenyan carpet viper, Echis pyramidus Leakyii. Attempts to crystallise it were unsuccessful. The structure of the Cobra neurotoxin was refined with the FAST data mentioned below.

The Structure of Papaya Protease Omega:

Papaya Protease Omega

This was solved during the HSO appointment at Reading. FAST data were processed and the structure solved by molecular replacement methods, as implemented in the CCP4 package and XPLOR. It was subsequently refined at 1.8Å resolution.

PDB Entry: 1PPO

Methodology Development Using the FAST Area Detector:

HDCA

This was the subject of the joint PDRA position at Liverpool and DL. It aimed at assessing the FAST area detector as a tool for data collection from very small crystals, in comparison with the Laue method. The tests included several small-molecule small crystals, of sizes in the range of 20 to 50 microns, as well as small crystals from proteins and oligonucleotide / peptide complexes. Test data were also collected from other systems: An Iridium derivative of the matrix Porin of E. Coli, was used to assess its usefulness for the Anomalous Dispersion method; high resolution data from the Cobra venom neurotoxin, up to 1.7Å.

E. Coli Glutamate Dehydrogenase:

This was the subject of the PDRA position at Leeds University. Precession and oscillation techniques were used to collect X-ray diffraction data from the above enzyme, on a rotating anode source, as well as at the SRS. Data processing and analysis, software development and graphical displays were done on a VAX 11/750. Gel column chromatography and activity assays were used for sample preparation and characterisation. Gel electrophoresis of the purified protein was used for further characterisation, prior to crystallisation. The data were eventually used in collaboration with the Sheffield University group (Prof. David W. Rice) to solve the structure.

Organic Semi-conductor Research:

This was the subject of the PhD thesis, gained at Nottingham University. During this research, several compounds were prepared de novo, their structures solved, and their electrical properties measured. Some explanations were made, to correlate the properties with the structures.

Other PDB entries: 1KI2, 1KIM, 1FCQ, 1FCU, 1FCV, 1PDO, 1JBO, 1PW9, 1PWB