IDENTIFICATION OF A NOVEL INHIBITORY ALLOSTERIC SITE OF p38 MAP KINASE

Juan Jesus Perez

Department of Chemical Engineering, Universitat Politecnica de Catalunya, BarcelonaTech, Spain

Abstract

The presentation I will report the discovery of a novel allosteric inhibitory site for p38a, a subclass of the mitogen-activated protein kinases (MAPK) family. The putative site was discovered after inspection of the crystallographic structure of the p38a-MK2 complex. MK2 (MAPK-activated protein kinase 2) is an interesting protein playing a dual role as inhibitor and substrate. This intriguing behavior is due to the ability of the two proteins to form distinctive heterodimers when p38a is phosphorylated or not. We hypothesized that the inhibitory action of MK2 is due to its ability to keep p38a in its inactive conformation and consequently, we investigated the atomic structure of the p38a-MK2 to understand such inhibitory behavior at the molecular level. For this purpose, two fragments of the MK2 regulatory loop in contact with p38a with sequences namely, Phe1-Tyr2-Ser3-Asn4-His5-Gly6-Leu7 (peptide-1) and [des-Phe1]-peptide-1 (peptide-2) in their zwitterionic form in vitro. Since both peptides showed inhibitory behavior, aimed at discovering small molecules peptidomimetics, we further characterized the peptide-p38a interaction. A pharmacophoric hypothesis was used as query for an in silico screening leading to the discovery of a fused ring compound that shows micromolar inhibitory activity. Site directed mutagenesis studies support that the compound binds to the putative novel allosteric site. We also will describe subsequent optimization work that lead to the discovery of a series of furazan derivatives with nanomolar inhibitory capabilities in the IL-1beta release assay in monocyte-derived macrophages isolated from human whole blood.

Keywords: Kinase allosteric inhibition, p38 inhibibition, novel allosteric site, furazan series of inhibitors.