Structural Basis Of ASK1-MKK4-JNK3 Complex
Mitogen-activated protein kinases (MAPKs), including C-Jun N-terminal kinases (JNK), are kinases that play a role in many cellular functions including apoptosis, differentiation, and survival. Mitogen-activated protein kinase kinases (MKKs) are enzymes of MAPKs, and MKKs are enzymes of mitogen-activated protein kinase kinase kinases (MAP3Ks). Our research aimed to determine the structural basis of the three-tier cascade interface of the interaction between MKK4 and its upstream MAP3K, ASK1. Here, an ASK1-MKK4-JNK3 complex, which was previously constructed by computational strategy, was simulated to analyze the dynamics of these three-tier kinase complexes. Furthermore, the major interfaces between ASK1 kinase domain and MKK4 kinase domain were verified by direct interaction assays. To study the three-protein complex, the simulation was run using nanoscale molecular dynamics (NAMD) and analyzed using visual molecular dynamics (VMD). The results showed that the complex is stable and the ASK1 interactions were determined. In addition, we also employed a integral computational method to exploit the interaction between ASK1 N-domain with downstream MKK4 & 7 substrates. The structural basis obtained in this study will demonstrate the molecular mechanism of ASK1-JNK cascades, which could provide the structural insights into other MAPK cascades. Further investigation is needed to fully characterize the structural basis of MAPK cascades that plays essential roles in differentiation, apoptosis, and survival as well as the many other cellular responses.