97 research outputs found
The multiple-specificity landscape of modular peptide recognition domains
Using large scale experimental datasets, the authors show how modular protein interaction domains such as PDZ, SH3 or WW domains, frequently display unexpected multiple binding specificity. The observed multiple specificity leads to new structural insights and accurately predicts new protein interactions
Structure of an Enzyme-Derived Phosphoprotein Recognition Domain
Membrane Associated Guanylate Kinases (MAGUKs) contain a protein interaction domain (GKdom) derived from the enzyme Guanylate Kinase (GKenz). Here we show that GKdom from the MAGUK Discs large (Dlg) is a phosphoprotein recognition domain, specifically recognizing the phosphorylated form of the mitotic spindle orientation protein Partner of Inscuteable (Pins). We determined the structure of the Dlg-Pins complex to understand the dramatic transition from nucleotide kinase to phosphoprotein recognition domain. The structure reveals that the region of the GKdom that once served as the GMP binding domain (GBD) has been co-opted for protein interaction. Pins makes significantly more contact with the GBD than does GMP, but primarily with residues that are conserved between enzyme and domain revealing the versatility of the GBD as a platform for nucleotide and protein interactions. Mutational analysis reveals that the GBD is also used to bind the GK ligand MAP1a, suggesting that this is a common mode of MAGUK complex assembly. The GKenz undergoes a dramatic closing reaction upon GMP binding but the protein-bound GKdom remains in the ‘open’ conformation indicating that the dramatic conformational change has been lost in the conversion from nucleotide kinase to phosphoprotein recognition domain
Signal transduction in a covalent post-assembly modification cascade
Natural reaction cascades control the movement of biomolecules between cellular compartments. Inspired by these systems, we report a synthetic reaction cascade employing post-assembly modification reactions to direct the partitioning of supramolecular complexes between phases. The system is composed of a self-assembled tetrazine-edged FeII8L12 cube and a maleimide-functionalized FeII4L6 tetrahedron. Norbornadiene (NBD) functions as the stimulus that triggers the cascade, beginning with the inverse-electron-demand Diels–Alder reaction of NBD with the tetrazine moieties of the cube. This reaction generates cyclopentadiene as a transient by-product, acting as a relay signal that subsequently undergoes a Diels–Alder reaction with the maleimide-functionalized tetrahedron. Cyclooctyne can selectively inhibit the cascade by outcompeting NBD as the initial trigger. Initiating the cascade with 2-octadecyl NBD leads to selective alkylation of the tetrahedron upon cascade completion. The increased lipophilicity of the C18-tagged tetrahedron drives this complex into a non-polar phase, allowing its isolation from the initially inseparable mixture of complexes
HDAC Inhibition Decreases the Expression of EGFR in Colorectal Cancer Cells
Epidermal growth factor receptor (EGFR), a receptor tyrosine kinase which
promotes cell proliferation and survival, is abnormally overexpressed in
numerous tumors of epithelial origin, including colorectal cancer (CRC). EGFR
monoclonal antibodies have been shown to increase the median survival and are
approved for the treatment of colorectal cancer. Histone deacetylases (HDACs),
frequently overexpressed in colorectal cancer and several malignancies, are
another attractive targets for cancer therapy. Several inhibitors of HDACs
(HDACi) are developed and exhibit powerful antitumor abilities. In this study,
human colorectal cancer cells treated with HDACi exhibited reduced EGFR
expression, thereby disturbed EGF-induced ERK and Akt phosphorylation. HDACi
also decreased the expression of SGLT1, an active glucose transporter found to
be stabilized by EGFR, and suppressed the glucose uptake of cancer cells. HDACi
suppressed the transcription of EGFR and class I HDACs were proved to be
involved in this event. Chromatin immunoprecipitation analysis showed that HDACi
caused the dissociation of SP1, HDAC3 and CBP from EGFR promoter. Our data
suggested that HDACi could serve as a single agent to block both EGFR and HDAC,
and may bring more benefits to the development of CRC therapy
Inflammation-Associated Nitrotyrosination Affects TCR Recognition through Reduced Stability and Alteration of the Molecular Surface of the MHC Complex
Nitrotyrosination of proteins, a hallmark of inflammation, may result in the production of MHC-restricted neoantigens that can be recognized by T cells and bypass the constraints of immunological self-tolerance. Here we biochemically and structurally assessed how nitrotyrosination of the lymphocytic choriomeningitis virus (LCMV)-associated immunodominant MHC class I-restricted epitopes gp33 and gp34 alters T cell recognition in the context of both H-2Db and H-2Kb. Comparative analysis of the crystal structures of H-2Kb/gp34 and H-2Kb/NY-gp34 demonstrated that nitrotyrosination of p3Y in gp34 abrogates a hydrogen bond interaction formed with the H-2Kb residue E152. As a consequence the conformation of the TCR-interacting E152 was profoundly altered in H-2Kb/NY-gp34 when compared to H-2Kb/gp34, thereby modifying the surface of the nitrotyrosinated MHC complex. Furthermore, nitrotyrosination of gp34 resulted in structural over-packing, straining the overall conformation and considerably reducing the stability of the H-2Kb/NY-gp34 MHC complex when compared to H-2Kb/gp34. Our structural analysis also indicates that nitrotyrosination of the main TCR-interacting residue p4Y in gp33 abrogates recognition of H-2Db/gp33-NY complexes by H-2Db/gp33-specific T cells through sterical hindrance. In conclusion, this study provides the first structural and biochemical evidence for how MHC class I-restricted nitrotyrosinated neoantigens may enable viral escape and break immune tolerance
What's that gene (or protein)? Online resources for exploring functions of genes, transcripts, and proteins
Isolation and Characterization of Acetylated Derivative of Recombinant Insulin Lispro Produced in Escherichia coli
The global burden of cancer attributable to risk factors, 2010-19: a systematic analysis for the Global Burden of Disease Study 2019
Application guide for omics approaches to cell signaling
Research in signal transduction aims to identify the functions of different signaling pathways in physiological and pathological states. Traditional techniques using biochemical, genetic or cell biological approaches have made important contributions to our understanding of cellular signaling. However, the single-gene approach does not take into account the full complexity of cell signaling. With the availability of omics techniques, great progress has been made in understanding signaling networks. Omics approaches can be classified into two categories: 'molecular profiling', including genomic, proteomic, post-translational modification and interactome profiling; and 'molecular perturbation', including genetic and functional perturbations
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