COMPARISON OF THE INTERACTION OF MKP3 (DUSP6) AND ITS SPLICE VARIANT WITH ERK BYDOCKING METHODOLOGY.

BIGI MM; MORI SEQUEIROS GARCÍA MM; COHEN SABBAN JM; CORNEJO MACIEL F; MALOBERTI PM; PAZ C

Mar del Plata

Congreso; LXVII ANNUAL MEETING OF SOCIEDAD ARGENTINA DE INVESTIGACIÓN CLÍNICA (SAIC); 2022

SAIC

MKP-3 is a dual activity enzyme member of the MAP Kinase Phosphatasesfamily. It is induced by proliferative stimuli and specific forphospho-ERK. The human MKP-3 gene generates the full-lengthtranscript or variant L, and an alternative spliced product or variantS, encoding MKP-3S or S protein. MKP-3L is a cytosolic proteinregulated by ERK-dependent phosphorylation. S protein lacks thenuclear export signal and a target residue for ERK phosphorylationinvolved in L protein stability. Accordingly, we have demonstrateddifferences between variants regarding stability, subcellular localizationand enzymatic activity measured by ERK dephosphorylation.The aim of this study was to gain insight on MKP-3 spatial structureby a bioinformatic approach to explain these differences and topredict additional functional differences between L and S proteins.From sequence alignments we found that an “acid loop” region,which includes the D262 residue crucial for the catalysis, is absentin S protein. In contrast, S protein retains its binding domain toERK2 through a kinase interaction motif (KIM). We simulated possibleinteractions between MKP-3 variants and ERK through dockingmethodology. From crystals structures 1HZM and 2FYS (PDB IDs)we simulated the ERK interaction with the KIM domain and MKP-3S.Then, we made the prediction of the interaction of the catalytic domainwith phosphatase activity and ERK, through aligning, refiningand docking structures 1MKP and 3ZUV. In all cases, the best modelsobtained achieved a high quality score (CAPRI RANK 3). Theresults suggest that although S protein could interact with ERK, itscatalytic activity would be altered. S protein could act as a negativedominant by interacting through the KIM domain and blocking L interactionwith ERK. Based on the analysis and the predictive modelsobtained, our current efforts focus on performing different mutationsand activity measurements on different substrates to validate theseresults.