Structural studies of p38 MAP kinase and its kinase kinase activator MKK6 in Atlantic salmon

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Project leader: Ass. professor Jorun B. Jørgensen


The p38 mitogen-activated protein kinase (p38 MAPK) is a member of a family of the enzymes that are activated by a variety of agents and conditions that generate cellular stress. These cellular stress responses include osmotic shock, UV light, heat shock, as well as response to the lipopolysacchrides (LPS) and CpG-motifs. The p38 MAPK are activated through phosphorylation on Thr and Tyr residues at the Thr-Gly-Tyr dual phosphorylation motif, respectively. Activation of p38 MAPK is mediated by the upstream MAPK kinases, referred to as MKK3 and MKK6. The p38 MAP kinase pathway plays a critical role in various signaling systems and has been shown to mediate signals for the generation of important biological responses such as phosphorylation of transcription factors, induction of cytokine production and induction of apoptosis. In mammalian species MAP kinases are involved in all aspects of immune responses, both adaptive and innate immunity.
Three Atlantic salmon p38 MAP kinase variants named Asp38a, Asp38b and Asp38b2 have been cloned. All three are 89-85% identical to the human p38¥á primary amino acid sequence. Additionally, the Atlantic salmon Asp38 MAP kinase activators named AsMKK3, AsMKK3b and AsMKK6 have been cloned. All three AsMKKs have high identity to the primary amino acid sequence of human MKK6 (85-80%) and MKK3b (74-72%). In vitro kinase assay showed that all three Asp38 variants are activated by AsMKK3, AsMKK3b and AsMKK6.Aims: The aim of the project is to further study the p38 MAP kinase signaling pathway with special emphasis on the immune system of Atlantic salmon. A subtask within this aim is to express the protein and to do structure analysis of AsMKK6.