A Peroxiredoxin-P38 MAPK scaffold increases MAPK activity by MAP3K-independent mechanisms

Summary Peroxiredoxins (Prdx) utilize reversibly oxidized cysteine residues to reduce peroxides but also to promote H 2 O 2 signal transduction, including H 2 O 2 -induced activation of P38 MAPK. Prdx form H 2 O 2 -induced disulfide complexes with many proteins, including multiple kinases involved in P38 MAPK signaling. Here we show that a genetically-encoded fusion between Prdx and the P38 MAPK is sufficient to hyperactivate the kinase in yeast and human cells by a mechanism that does not require the H 2 O 2 -sensing cysteine of the Prdx. In yeast, we demonstrate that a P38-Prdx fusion protein compensates for the loss of a scaffold protein and upstream MAP3K kinase activity, driving entry into mitosis. Based on our findings, we propose that the H 2 O 2 -induced formation of Prdx-MAPK disulfide complexes provides a scaffold and signaling platform for MAPKK-MAPK signaling. The demonstration that formation of a complex with a Prdx can be sufficient to modify the activity of a kinase has broad implications for peroxide-based signal transduction in eukaryotes. Highlights P38-Prdx complexes increase P38 (Sty1/MAPK14) phosphorylation in yeast and human cells The S. pombe Prdx promotes transient thioredoxin-mediated oxidation of a MAPK tyrosine phosphatase P38-Prdx complexes increase P38(Sty1) activity by phosphatase and MAP3K-independent mechanisms P38-Prdx complexes increase the stability and phosphorylation of the S. pombe P38 MAPKK (Wis1) Non-canonical, H 2 O 2 -induced autophosphorylation contributes to activation of the Wis1 MAPKK