W0475

Structures of Active MK2 in Complex with Staurosporine and ADP Reveal Differences with the Auto-inhibited Enzyme. Kevin Parris, Karhryn Underwood, Elizabeth Federico, Chu-Lai Hsaio, Lidia Mosyak, Robert Czerwinski, Tania Shane, Meggin Taylor, Kristine Svenson, Yan Liu, Chemical and Screening Sciences, Wyeth Research, 200 Cambridge Park Dr., Cambridge, MA 02140.

MAP KAP kinase 2 (MK2), a Ser/Thr kinase, plays a crucial role in the inflammatory process. We have determined the crystal structures of a catalytically active C-terminal deletion form of human MK2, residues 41-364, in complex with staurosporine at 2.7Å and with ADP at 3.2Å, revealing overall structural similarity with other Ser/Thr kinases. Kinetic analysis reveals that the K_m for ATP is very similar for ΜΚ2 41-364 as compared to p38 activated MK2 41-400. Conversely, the catalytic rate and binding for peptide substrate are dramatically reduced in ΜΚ2 41-364. However, phosphorylation of MK2 41-364 by p38 restores the V_max and K_m for peptide substrate to values comparable to those seen in p38 activated MK2 41-400, suggesting a mechanism for regulation of enzyme activity.