title: Structural basis of autoregulatory scaffolding by apoptosis signal-regulating kinase 1.
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 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.
authors.affiliation: Biochemistry Department, School of Biomedical Sciences, University of Otago, Dunedin 9054, New Zealand.
authors.forename: Johannes F
authors.initials: JF
authors.lastname: Weijman
authors.affiliation: Biochemistry Department, School of Biomedical Sciences, University of Otago, Dunedin 9054, New Zealand.
authors.forename: Abhishek
authors.initials: A
authors.lastname: Kumar
authors.affiliation: Biochemistry Department, School of Biomedical Sciences, University of Otago, Dunedin 9054, New Zealand.
authors.forename: Sam A
authors.initials: SA
authors.lastname: Jamieson
authors.affiliation: Biochemistry Department, School of Biomedical Sciences, University of Otago, Dunedin 9054, New Zealand.
authors.forename: Chontelle M
authors.initials: CM
authors.lastname: King
authors.affiliation: Australian Synchrotron, Clayton, VIC 3168, Australia.
authors.forename: Tom T
authors.initials: TT
authors.lastname: Caradoc-Davies
authors.affiliation: Biochemistry Department, School of Biomedical Sciences, University of Otago, Dunedin 9054, New Zealand.
authors.forename: Elizabeth C
authors.initials: EC
authors.lastname: Ledgerwood
authors.affiliation: The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia.|Department of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia.
authors.forename: James M
authors.initials: JM
authors.lastname: Murphy
authors.affiliation: Biochemistry Department, School of Biomedical Sciences, University of Otago, Dunedin 9054, New Zealand; peter.mace@otago.ac.nz.
authors.forename: Peter D
authors.identifier: 0000-0003-2175-9537
authors.initials: PD
authors.lastname: Mace
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D006801:Humans; D048669:MAP Kinase Kinase 6 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D048848:MAP Kinase Kinase Kinase 5 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D008958:Models, Molecular; D009154:Mutation; D010766:Phosphorylation; D011485:Protein Binding; D011487:Protein Conformation; D054730:Protein Interaction Domains and Motifs; D015398:Signal Transduction; D013329:Structure-Activity Relationship; D013379:Substrate Specificity
chemical_list: D048848:MAP Kinase Kinase Kinase 5; D048669:MAP Kinase Kinase 6
keywords: ASK1; MAP kinase; MKK6; scaffolding; signaling