Dataset Information

Structural and Functional Characterization of the JH2 Pseudokinase Domain of JAK Family Tyrosine Kinase 2 (TYK2).

ABSTRACT: JAK (Janus family of cytoplasmic tyrosine kinases) family tyrosine kinase 2 (TYK2) participates in signaling through cytokine receptors involved in immune responses and inflammation. JAKs are characterized by dual kinase domain: a tyrosine kinase domain (JH1) that is preceded by a pseudokinase domain (JH2). The majority of disease-associated mutations in JAKs map to JH2, demonstrating its central regulatory function. JH2s were considered catalytically inactive, but JAK2 JH2 was found to have low autoregulatory catalytic activity. Whether the other JAK JH2s share ATP binding and enzymatic activity has been unclear. Here we report the crystal structure of TYK2 JH2 in complex with adenosine 5'-O-(thiotriphosphate) (ATP-?S) and characterize its nucleotide binding by biochemical and biophysical methods. TYK2 JH2 did not show phosphotransfer activity, but it binds ATP and the nucleotide binding stabilizes the protein without inducing major conformational changes. Mutation of the JH2 ATP-binding pocket increased basal TYK2 phosphorylation and downstream signaling. The overall structural characteristics of TYK2 JH2 resemble JAK2 JH2, but distinct stabilizing molecular interactions around helix ?AL in the activation loop provide a structural basis for differences in substrate access and catalytic activities among JAK family JH2s. The structural and biochemical data suggest that ATP binding is functionally important for both TYK2 and JAK2 JH2s, whereas the regulatory phosphorylation appears to be a unique property of JAK2. Finally, the co-crystal structure of TYK2 JH2 complexed with a small molecule inhibitor demonstrates that JH2 is accessible to ATP-competitive compounds, which offers novel approaches for targeting cytokine signaling as well as potential therapeutic applications.

SUBMITTER: Min X

PROVIDER: S-EPMC4646372 | biostudies-literature | 2015 Nov

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Structural and Functional Characterization of the JH2 Pseudokinase Domain of JAK Family Tyrosine Kinase 2 (TYK2).

Min Xiaoshan X Ungureanu Daniela D Maxwell Sarah S Hammarén Henrik H Thibault Steve S Hillert Ellin-Kristina EK Ayres Merrill M Greenfield Brad B Eksterowicz John J Gabel Chris C Walker Nigel N Silvennoinen Olli O Wang Zhulun Z

The Journal of biological chemistry 20150910 45

JAK (Janus family of cytoplasmic tyrosine kinases) family tyrosine kinase 2 (TYK2) participates in signaling through cytokine receptors involved in immune responses and inflammation. JAKs are characterized by dual kinase domain: a tyrosine kinase domain (JH1) that is preceded by a pseudokinase domain (JH2). The majority of disease-associated mutations in JAKs map to JH2, demonstrating its central regulatory function. JH2s were considered catalytically inactive, but JAK2 JH2 was found to have low ...[more]

PMID: 26359499

Similar Datasets

Project description:Tyrosine kinase 2 (Tyk2), a central component of Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling, has major effects on innate immunity and inflammation. Mice lacking Tyk2 are resistant to endotoxin shock induced by lipopolysaccharide (LPS), and Tyk2 deficient macrophages fail to efficiently induce interferon alpha/beta after LPS treatment. However, how Tyk2 globally regulates transcription of downstream target genes remains unknown. Here we examine the regulatory role of Tyk2 in basal and inflammatory transcription by comparing gene expression profiles of peritoneal macrophages from Tyk2 mutant and wildtype control mice that were either kept untreated or exposed to LPS for six hours.Untreated Tyk2-deficient macrophages exhibited reduced expression of immune response genes relative to wildtype, in particular those that contain interferon response elements (IRF/ISRE), whereas metabolic genes showed higher expression. Upon LPS challenge, IFN-inducible genes (including those with an IRF/ISRE transcription factor binding-site) were strongly upregulated in both Tyk2 mutant and wildtype cells and reached similar expression levels. In contrast, metabolic gene expression was strongly decreased in wildtype cells upon LPS treatment, while in Tyk2 mutant cells the expression of these genes remained relatively unchanged, which exaggerated differences already present at the basal level. We also identified several 5'UR transcription factor binding-sites and 3'UTR regulatory elements that were differentially induced between Tyk2 deficient and wildtype macrophages and that have not previously been implicated in immunity.Although Tyk2 is essential for the full LPS response, its function is mainly required for baseline expression but not LPS-induced upregulation of IFN-inducible genes. Moreover, Tyk2 function is critical for the downregulation of metabolic genes upon immune challenge, in particular genes involved in lipid metabolism. Together, our findings suggest an important regulatory role for Tyk2 in modulating the relationship between immunity and metabolism.

Dataset Information

Structural and Functional Characterization of the JH2 Pseudokinase Domain of JAK Family Tyrosine Kinase 2 (TYK2).

Publications

Structural and Functional Characterization of the JH2 Pseudokinase Domain of JAK Family Tyrosine Kinase 2 (TYK2).

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets