Search results for "Kinase activity"

2020

The assembly of human cytomegalovirus (HCMV) virions is an orchestrated process that requires, as an essential prerequisite, the complex crosstalk between viral structural proteins. Currently, however, the mechanisms governing the successive steps in the constitution of virion protein complexes remain elusive. Protein phosphorylation is a key regulator determining the sequential changes in the conformation, binding, dynamics, and stability of proteins in the course of multiprotein assembly. In this review, we present a comprehensive map of the HCMV virion proteome, including a refined view on the virion phosphoproteome, based on previous publications supplemented by new results. Thus, a nov…

Plasticity of the PAS domain and a potential role for signal transduction in the histidine kinase DcuS

2008

The mechanistic understanding of how membrane-embedded sensor kinases recognize signals and regulate kinase activity is currently limited. Here we report structure-function relationships of the multidomain membrane sensor kinase DcuS using solid-state NMR, structural modeling and mutagenesis. Experimental data of an individual cytoplasmic Per-Arnt-Sim (PAS) domain were compared to structural models generated in silico. These studies, together with previous NMR work on the periplasmic PAS domain, enabled structural investigations of a membrane-embedded 40-kDa construct by solid-state NMR, comprising both PAS segments and the membrane domain. Structural alterations are largely limited to prot…

The Nature of the Stimulus and of the Fumarate Binding Site of the Fumarate Sensor DcuS of Escherichia coli

2005

DcuS is a membrane-associated sensory histidine kinase of Escherichia coli specific for C(4) -dicarboxylates. The nature of the stimulus and its structural prerequisites were determined by measuring the induction of DcuS-dependent dcuB'-'lacZ gene expression. C(4)-dicarboxylates without or with substitutions at C2/C3 by hydrophilic (hydroxy, amino, or thiolate) groups stimulated gene expression in a similar way. When one carboxylate was replaced by sulfonate, methoxy, or nitro groups, only the latter (3-nitropropionate) was active. Thus, the ligand of DcuS has to carry two carboxylate or carboxylate/nitro groups 3.1-3.8 A apart from each other. The effector concentrations for half-maximal i…

SIRT1 prevents genotoxic stress-induced p53 activation in acute myeloid leukemia

2014

SIRT1 is an important regulator of cellular stress response and genomic integrity. Its role in tumorigenesis is controversial. Whereas sirtuin 1 (SIRT1) can act as a tumor suppressor in some solid tumors, increased expression has been demonstrated in many cancers, including hematologic malignancies. In chronic myeloid leukemia, SIRT1 promoted leukemia development, and targeting SIRT1 sensitized chronic myeloid leukemia progenitors to tyrosine kinase inhibitor treatment. In this study, we investigated the role of SIRT1 in acute myeloid leukemia (AML). We show that SIRT1 protein, but not RNA levels, is overexpressed in AML samples harboring activating mutations in signaling pathways. In FMS-l…

MCC1019, a selective inhibitor of the Polo-box domain of Polo-like kinase 1 as novel, potent anticancer candidate

2019

Polo-like kinase (PLK1) has been identified as a potential target for cancer treatment. Although a number of small molecules have been investigated as PLK1 inhibitors, many of which showed limited selectivity. PLK1 harbors a regulatory domain, the Polo box domain (PBD), which has a key regulatory function for kinase activity and substrate recognition. We report on 3-bromomethyl-benzofuran-2-carboxylic acid ethyl ester (designated: MCC1019) as selective PLK1 inhibitor targeting PLK1 PBD. Cytotoxicity and fluorescence polarization-based screening were applied to a library of 1162 drug-like compounds to identify potential inhibitors of PLK1 PBD. The activity of compound MC1019 against the PLK1…

Modulation of Hedgehog target gene expression by the Fused serine-threonine kinase in wing imaginal discs

1998

0925-4773 doi: DOI: 10.1016/S0925-4773(98)00130-0; The Fused (Fu) serine–threonine kinase and the Suppressor of fused (Su(fu)) product are part of the Hedgehog (Hh) signalling pathway both in embryos and in imaginal discs. In wing imaginal discs, the Hh signal induces Cubitus interruptus (Ci) accumulation and activates patched (ptc) and decapentaplegic (dpp) expression along the anterior/posterior (A/P) boundary. In this paper, we have examined the role of the Fu and Su(fu) proteins in the regulation of Hh target gene expression in wing imaginal discs, by using different classes of fu alleles and an amorphic Su(fu) mutation. We show that, at the A/P boundary, Fu kinase activity is involved …

2015

Multidrug resistance is a prevailing phenomenon leading to chemotherapy treatment failure in cancer patients. In the current study two known cytotoxic pseudoguaianolide sesquiterpene lactones; neoambrosin (1) and damsin (2) that circumvent MDR were identified. The two cytotoxic compounds were isolated using column chromatography, characterized using 1D and 2D NMR, MS, and compared with literature values. The isolated compounds were investigated for their cytotoxic potential using resazurin assays and thereafter confirmed with immunoblotting and in silico studies. MDR cells overexpressing ABC transporters (P-glycoprotein, BCRP, ABCB5) did not confer cross-resistance toward (1) and (2), indic…

A supramolecular complex in the environmental stress signalling pathway of Bacillus subtilis

2003

SigmaB, an alternative sigma-factor of Bacillus subtilis, mediates the response of the cell to a variety of physical insults. Within the environmental stress signalling pathway RsbU, a protein phosphatase, is stimulated by its interaction with the protein kinase RsbT. In the absence of stress RsbT is expected to be trapped by an alternative binding partner, RsbS. Here, we have demonstrated that RsbS alone cannot act as an alternative partner for RsbT, but instead requires the presence of RsbR to create a high molecular mass RsbR:RsbS complex (approximately 1 MDa) able to capture RsbT. In this complex the phosphorylation state of RsbS, and not that of RsbR, controlled the binding to RsbT, wh…

Met inhibition revokes IFNγ-induction of PD-1 ligands in MET-amplified tumours

2019

BACKGROUND: Interferon-induced expression of programmed cell death ligands (PD-L1/PD-L2) may sustain tumour immuneevasion. Patients featuring MET amplification, a genetic lesion driving transformation, may benefit from anti-MET treatment. We explored if MET-targeted therapy interferes with Interferon-gamma modulation of PD-L1/PD-L2 in MET-amplified tumours.METHODS: PD-L1/PD-L2 expression and signalling pathways downstream of MET or Interferon-gamma were analysed in MET-amplified tumour cell lines and in patient-derived tumour organoids, in basal condition, upon Interferon-gamma stimulation, and after anti-MET therapy.RESULTS: PD-L1 and PD-L2 were upregulated in MET-amplified tumour cells up…

B-Raf Acts via the ROCKII/LIMK/Cofilin Pathway To Maintain Actin Stress Fibers in Fibroblasts

2004

Members of the Raf family of serine/threonine protein kinases have been well studied in a variety of organisms ranging from Drosophila to humans. Three raf homologues (raf-1, B-raf, and A-raf) exist in mammals, while a single prototypic homologue exists in lower organisms. A wealth of genetic and biochemical data have indicated that Raf family members are signaling kinases that are integral components of the conserved Ras/Raf/MEK/ERK signaling cascade. Following activation by Ras-dependent mechanisms, Raf protein kinases act as mitogen-activated protein (MAP) kinase kinase kinases, which phosphorylate and activate the type 1/2 MAP kinase kinases, also known as MEK1/2. These dual-specificity…