ABSTRACT
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.
Subject(s)
Cyclin-Dependent Kinase 2/chemistry , Crystallography, X-Ray , Humans , Protein ConformationABSTRACT
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.
Subject(s)
Anti-Inflammatory Agents, Non-Steroidal/chemical synthesis , Intracellular Signaling Peptides and Proteins/antagonists & inhibitors , Protein Serine-Threonine Kinases/antagonists & inhibitors , Pyrazoles/chemical synthesis , Pyrimidines/chemical synthesis , Animals , Anti-Inflammatory Agents, Non-Steroidal/pharmacokinetics , Anti-Inflammatory Agents, Non-Steroidal/pharmacology , Cell Line , Crystallography, X-Ray , HSP27 Heat-Shock Proteins/metabolism , Humans , Intracellular Signaling Peptides and Proteins/chemistry , Lipopolysaccharides/pharmacology , Male , Mice , Mice, Inbred C57BL , Models, Molecular , Phosphorylation , Protein Conformation , Protein Serine-Threonine Kinases/chemistry , Pyrazoles/pharmacokinetics , Pyrazoles/pharmacology , Pyrimidines/pharmacokinetics , Pyrimidines/pharmacology , Shock, Septic/metabolism , Small Molecule Libraries , Stereoisomerism , Structure-Activity Relationship , Tumor Necrosis Factor-alpha/biosynthesisABSTRACT
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.
