Structural Characterization of the Apoptosis Signal‐regulating Kinase 1 (ASK1) Domain Responsible for Thioredoxin Binding and its Complex

0533796 - ÚOCHB 2021 US eng A - Abstract
Obšil, T. - Pšenáková, K. - Hexnerová, Rozálie - Srb, Pavel - Obšilová, Veronika - Veverka, Václav
Structural Characterization of the Apoptosis Signal‐regulating Kinase 1 (ASK1) Domain Responsible for Thioredoxin Binding and its Complex.
FASEB Journal. Wiley. Roč. 34, S1 (2020). ISSN 0892-6638. E-ISSN 1530-6860.
[Annual Meeting on Experimental Biology. 04.04.2020-07.04.2020, San Diego]
R&D Projects: GA ČR(CZ) GA19-00121S; GA MŠMT(CZ) EF16_019/0000729
Institutional support: RVO:61388963 ; RVO:67985823
Keywords : ASK1 * thioredoxin
OECD category: Biochemistry and molecular biology
https://doi.org/10.1096/fasebj.2020.34.s1.03959

Apoptosis signal‐regulating kinase 1 (ASK1) is a mitogen‐activated protein kinase kinase kinase 5 implicated in p38 mitogen‐activated protein kinase and c‐Jun N‐terminal kinase signaling cascades. ASK1 responds to a wide range of signaling cues and is dysregulated in cancer, neurodegeneration and cardiovascular diseases. The catalytic activity of ASK1 is tightly controlled through oligomerization and binding of several cofactors, among which thioredoxin stands out as the most important ASK1 inhibitor. Interestingly, only the reduced form of thioredoxin inhibits ASK1 by direct binding to its N‐terminal domain and oxidation‐driven thioredoxin dissociation is the key event in oxidative stress‐mediated ASK1 activation. Despite extensive efforts, the molecular basis of this key cellular regulatory mechanism has remained unknown until now, primarily due to the dynamic properties of the ASK1 N‐terminal domain, which has prevented its structural characterization by X‐ray crystallography. Here, we report the structural characterization of the ASK1 domain responsible for thioredoxin binding and of the ASK1: thioredoxin complex using NMR spectroscopy and chemical cross‐linking, which provides the molecular basis for complex dissociation under oxidative stress conditions. Our data reveal that the N‐terminal domain of ASK1 adopts a fold resembling the thioredoxin structure while retaining substantial conformational plasticity at the thioredoxin‐binding interface. Although oxidative stress induces relatively moderate structural changes in thioredoxin, we show that these changes lead to a substantial conformational rearrangement of the thioredoxin‐binding interface on ASK1 driven by the formation of intramolecular disulfide bridges. Lastly, we demonstrate that the cysteine residue at the position 250 of ASK1 is the key element of this molecular switch.
Permanent Link: http://hdl.handle.net/11104/0312434