Searching for a small-molecule anti-inflammatory treatment
Chronic and acute inflammation is linked to several human diseases, such as eczema, multiple sclerosis and rheumatoid arthritis. Understanding the crystal structure of serine/threonine protein kinases (or MAP kinases), signalling molecules that play a specific role in the immune response against a variety of environmental challenges, is necessary in order to develop novel, nonbiological antiinflammatory therapeutics. Scientists from Evotec, a company that specialises in the discovery and the development of novel small molecule drugs, have used one of Diamond’s Macromolecular Crystallography beamlines (I02) to reveal the first high resolution crystal structure of MK3, a MAP kinase, in complex with a pharmaceutical lead compound.
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Tumour necrosis factor alpha (TNFα) is a cytokine involved in the immune regulation and the inflammatory response, the latter being associated with immune diseases such as psoriasis and rheumatoid arthritis. The Mapkap kinases 2 and 3 (MK2 and MK3) have been implicated in intracellular signalling pathways leading to the production of TNFα: it has been observed that the disruption of MK2 in mice has led to the reduction in TNFα production and, although the disruption of MK3 shows no effect, the MK2 and MK3 double knock-out shows a relatively stronger effect on TNFα production than the MK2 knock-out alone. Hence, an anti-inflammatory treatment could be based on the development of inhibitors targeting MK2. The biopharmaceutical industry has pursued this route for many years but unfortunately these efforts have been hindered by difficulties in getting a high resolution crystal structure for MK2. The resolution levels obtained previously in the 2.6 to 3.2 Å range, do not enable researchers to gather precise details of the binding interactions of ligands, such as a potential inhibitor. However, the high sequence homology between MK2 and MK3 suggests that MK3 could be used as a model for the MK2/MK3 family and for the design of MK3 and MK2 inhibitors. To this end, the Evotec team designed several MK3 constructs and managed to produce one that yielded highly diffracting crystals when in complex with a pharmaceutical lead compound. The Macromolecular Crystallography beamline enabled the industrial users to obtain the first high resolution (1.9 Å) structure of MK3; it confirms that MK3 has an active site pocket that closely resembles that of MK2, with differences not being directly involved in ligand interaction. It also gives intricate details around the active site pocket such as the water interaction network that could be instrumental in guiding structure-based drug design.
The structure of MK3 should serve as a surrogate in the design of selective inhibitors against MK2 but the Evotec team is considering a MK3 chimeric protein having all the MK2 active site residues within 4 to 6 Å distance from the ligand.
Dr John Barker is from Evotec.
structures of chimeras of MK3 (designed to mimic the MK2 active site) Evotec anticipates unravelling the subtle structural differences which lead to the variation of Structure Activity Relationships (SAR) of inhibitors across the MK family of kinases. Through the high resolution structures, enabled by the Diamond Light Source, Evotec is adding to the knowledge of the scientific community working on an increasingly interesting set of targets in the therapeutic area of inflammatory disease.”
Dr John Barker, Evotec
High resolution crystal structure of human Mapkap kinase 3 in complex with a high affinity ligand, Cheng R, Felicetti B, Palan S, Toogood-Johnson I, Scheich C, Barker J, Whittaker M and Hesterkamp T. Protein Science 2010, Vol 19:168-173
DOI: 10.1002/pro.294
For more information on I02, please contact thomas.sorensen@diamond.ac.uk