Crystal structure of human cyclin-dependent kinase-2 complex with MK2 inhibitor TEI-I01800: insight into the selectivity.

Mitogen-activated protein kinase-activated protein kinase 2 (MK2 or MAPKAP-K2) is a Ser/Thr kinase from the p38 mitogen-activated protein kinase signalling pathway and plays an important role in inflammatory diseases. The crystal structure of the MK2-TEI-I01800 complex has been reported; its Gly-rich loop was found to form an α-helix, not a ß-sheet as has been observed for other Ser/Thr kinases. TEI-I01800 is 177-fold selective against MK2 compared with CDK2; in order to understand the inhibitory mechanism of TEI-I01800, the cyclin-dependent kinase 2 (CDK2) complex structure with TEI-I01800 was determined at 2.0 Å resolution. Interestingly, the Gly-rich loop of CDK2 formed a ß-sheet that was different from that of MK2. In MK2, TEI-I01800 changed the secondary structure of the Gly-rich loop from a ß-sheet to an α-helix by collision between Leu70 and a p-ethoxyphenyl group at the 7-position and bound to MK2. However, for CDK2, TEI-I01800 bound to CDK2 without this structural change and lost the interaction with the substituent at the 7-position. In summary, the results of this study suggest that the reason for the selectivity of TEI-I01800 is the favourable conformation of TEI-I01800 itself, making it suitable for binding to the α-form MK2.

Structural analysis of an MK2-inhibitor complex: insight into the regulation of the secondary structure of the Gly-rich loop by TEI-I01800.

Mitogen-activated protein kinase-activated protein kinase 2 (MAPKAP-K2 or MK2) is a Ser/Thr kinase from the p38 mitogen-activated protein kinase signalling pathway and plays an important role in inflammatory diseases. The crystal structure of the complex of human MK2 (residues 41-364) with the potent MK2 inhibitor TEI-I01800 (pK(i) = 6.9) was determined at 2.9 A resolution. The MK2 structure in the MK2-TEI-I01800 complex is composed of two domains, as observed for other Ser/Thr kinases; however, the Gly-rich loop in the N-terminal domain forms an alpha-helix structure and not a beta-sheet. TEI-I01800 binds to the ATP-binding site as well as near the substrate-binding site of MK2. Both TEI-I01800 molecules have a nonplanar conformation that differs from those of other MK2 inhibitors deposited in the Protein Data Bank. The MK2-TEI-I01800 complex structure is the first active MK2 with an alpha-helical Gly-rich loop and TEI-I01800 regulates the secondary structure of the Gly-rich loop.

Mitogen-activated protein kinase-activated protein kinase 2 (MAPKAP-K2) as an antiinflammatory target: discovery and in vivo activity of selective pyrazolo[1,5-a]pyrimidine inhibitors using a focused library and structure-based optimization approach.

A novel class of mitogen-activated protein kinase-activated protein kinase 2 (MAPKAP-K2) inhibitors was discovered through screening a kinase-focused library. A homology model of MAPKAP-K2 was generated and used to guide the initial SAR studies and to rationalize the observed selectivity over CDK2. An X-ray crystal structure of a compound from the active series bound to crystalline MAPKAP-K2 confirmed the predicted binding mode. This has enabled the discovery of a series of pyrazolo[1,5-a]pyrimidine derivatives showing good in vitro cellular potency as anti-TNF-α agents and in vivo efficacy in a mouse model of endotoxin shock.