Structural basis of autoregulatory scaffolding by apoptosis signal-regulating kinase 1.Weijman, J.F., Kumar, A., Jamieson, S.A., King, C.M., Caradoc-Davies, T.T., Ledgerwood, E.C., Murphy, J.M., Mace, P.D.
(2017) Proc. Natl. Acad. Sci. U.S.A. 114: E2096-E2105
- PubMed: 28242696
- DOI: 10.1073/pnas.1620813114
- PubMed Abstract:
Apoptosis signal-regulating kinases (ASK1-3) are apical kinases of the p38 and JNK MAP kinase pathways. They are activated by diverse stress stimuli, including reactive oxygen species, cytokines, and osmotic stress; however, a molecular understanding ...
Apoptosis signal-regulating kinases (ASK1-3) are apical kinases of the p38 and JNK MAP kinase pathways. They are activated by diverse stress stimuli, including reactive oxygen species, cytokines, and osmotic stress; however, a molecular understanding of how ASK proteins are controlled remains obscure. Here, we report a biochemical analysis of the ASK1 kinase domain in conjunction with its N-terminal thioredoxin-binding domain, along with a central regulatory region that links the two. We show that in solution the central regulatory region mediates a compact arrangement of the kinase and thioredoxin-binding domains and the central regulatory region actively primes MKK6, a key ASK1 substrate, for phosphorylation. The crystal structure of the central regulatory region reveals an unusually compact tetratricopeptide repeat (TPR) region capped by a cryptic pleckstrin homology domain. Biochemical assays show that both a conserved surface on the pleckstrin homology domain and an intact TPR region are required for ASK1 activity. We propose a model in which the central regulatory region promotes ASK1 activity via its pleckstrin homology domain but also facilitates ASK1 autoinhibition by bringing the thioredoxin-binding and kinase domains into close proximity. Such an architecture provides a mechanism for control of ASK-type kinases by diverse activators and inhibitors and demonstrates an unexpected level of autoregulatory scaffolding in mammalian stress-activated MAP kinase signaling.
Biochemistry Department, School of Biomedical Sciences, University of Otago, Dunedin 9054, New Zealand.