Protein Refinement and Engineering


Principal Investigator

David Ollis

Research School of Chemistry


We are interested in understanding how importand biological molecules function. Our work starts with the structure determination of these molecules and them moves onto biochemical experiments. Our current work is focussed on three systems.

1. PII Protein,

2. Bikunin, and

3. Peptidyl-Prolyl Isomerase (PPI B).




Paul Carr

Karen Edwards

Eong Cheah

Yibin Xu

Anna Robinson

Research School of Chemistry




s06 - VPP, PC


What are the results to date and the future of the work?

In the last year, the structure of PII protein in a complex with ATP and a ketoglutarate has been solved. The ATP bindng site has been identified, but the a ketoglutarate and a long loop of the protein appear to be disordered and hence, invisible in our electron density maps.

The structure of the bikunin molecule has revealed how the two protease inhibitor domains are oriented. Although the two inhibition sites are exposed, they appear to be sufficiently close to each other to prevent binding two serine proteases at the same time. This may have some relevance to understanding how proteases control in cell growth and other processes.

The structure of E. coli PPI B has been determined. Comparison of this structure with that of the peptide bound form of the protein suggests that the mobility of loops maybe important in the catalytic action of the enzyme.

What computational techniques are used?

The supercomputer is now used in all aspects of structure determination: data processing, structure determination and structure refinement. Data processing involves the analysis of diffraction images whicle structure determination involves a variety of techniques. This work is currently done with the CCP4 programs. The most computer intensive part of our work is structure refinement for which the X-plor program is used.


- Appendix A





Carr, P.D., Cheah, U.E., Suffolk, P.M., Vasudevan, S.G., Dixon, N.E. & Ollis,D.L. X-Ray Structure of the Signal Transducing Protein PII from Escherichia coli at 1.9 Å. ACTA Cryst D, (1996) D52, 93-104.

Edwards, K.J., Barton, J,D., Rossjohn, J.Thorn, J.M., Taylor, G. & Ollis, D.L. Structural Comparison of Three Medium Chain Dehydrogenases: Functional and Evolutionary Implications Arc. Biophys. Biochem., (1996) 328, 173-183.

Edwards, K.J., Suffolk, P.M. Carr, P.D. Wegman, M., Cheah, E. and Ollis, D.L. Crystallization and Preliminary X-ray Diffraction Studies of New Crystal Forms of Escherichia coli PII Complexed with Various Ligands. ACTA Cryst D (1996) 52 738-742.

Jaggi, R., Ybarluccea,W., Cheah, E., Carr, P.D., Edwards, K.J., Ollis,D.L. and Vasudevan, S.G. The role of the T loop of the signal transducing protein PII from Escherichia coli FEBS Lett , (1996), 391 223-228.