MIPS FOR PROTEIN CRYSTALS

Almost all prescription drugs on the market, which account for billions of pounds in annual sales worldwide, directly or indirectly target proteins. Protein functions are determined by their three-dimensional structures, hence detailed understanding of protein structure is essential for rational design of therapeutic treatments. Examples include cancer, obesity, cardiovascular disorders, autoimmune diseases and a multitude of other ailments.

The most powerful method for determining the structure of proteins is X-ray crystallography which is totally reliant on the availability of high quality crystals. However, the production of useful crystals has always been, and still remains, the bottleneck to structure determination¹.

There is no ‘magic bullet’ that will guarantee the yield of good crystals, hence rational approaches leading to the development of new and improved technologies for obtaining high quality crystals is of crucial importance to progress.

Nucleation is the first step that determines crystal formation hence the ability to control nucleation would tackle the problem at its conception. A search for a ‘universal’ nucleant - a substance that can induce nucleation of any protein, is therefore on-going.

To date, nucleation has been facilitated mainly by seeding, epitaxy, charged surfaces or mechanical means, but none of these have proved to be of general use.

This talk will discuss a completely new approach² that has led to a unique means of producing protein crystals by designing ‘smart materials’, namely molecularly imprinted polymers (MIPs) as templates for crystallization³. The idea was to find a material that would specifically attract protein molecules to come together and form a crystal. Imprinting with protein molecules creates a fingerprint of the protein on the polymer, thereby enabling the MIP to serve as a tailor-made nucleant for crystal formation⁴. The presence of MIPs in crystallization trials resulted in faster formation of crystals and major improvement in their quality^3,5. Furthermore, the design of a new generation of MIPs provides a significant advance in the field by introducing the first non-protein nucleating agents for crystallising any bio-macromolecule in high throughput nanoscale experiments^6,7.

References

[1] Chayen N.E. and Saridakis E. (2008) Protein crystallization: from purified protein to diffraction-quality crystal. Nature Methods 5: 147-153.

[2] Nanev C., Saridakis E. and Chayen N.E. (2017) Protein crystal nucleation in pores. Scientific Reports Nature Publishing Group 7:35821.

[3] Saridakis et al. (2011) Protein crystallization facilitated by molecularly imprinted polymers. Proc. Natl. Acad. Sci. U.S.A. 108: 11081-11086.

[4] Saridakis E. and Chayen N.E. (2013) Polymers assisting in protein crystallization. Trends in Biotechnology 31: 515-520

[5] Khurshid et al. (2014) Porous nucleating agents for protein crystallization. Nature Protocols 9:Pages: 1621–1633.

[6] Khurshid et al. (2015) Automating the application of smart materials for protein crystallization. Acta Cryst D 71: 534–540.

[7] http://quicktech.imperialinnovations.co.uk/i/materials/CRMIP.html