Search results for "Phosphorylation"
showing 10 items of 975 documents
Mechanistic insights into the phosphoryl transfer reaction in cyclin-dependent kinase 2: a QM/MM study
2019
AbstractCyclin-dependent kinase 2 (CDK2) is an important member of the CDK family exerting its most important function in the regulation of the cell cycle. It catalyzes the transfer of the gamma phosphate group from an ATP (adenosine triphosphate) molecule to a Serine/Threonine residue of a peptide substrate. Due to the importance of this enzyme, and protein kinases in general, a detailed understanding of the reaction mechanism is desired. Thus, in this work the phosphoryl transfer reaction catalyzed by CDK2 was revisited and studied by means of hybrid quantum mechanics/molecular mechanics (QM/MM) calculations. Our results show that the base-assisted mechanism is preferred over the substrat…
Flexible Structure of Peptide-Bound Filamin A Mechanosensor Domain Pair 20-21.
2015
Filamins (FLNs) are large, multidomain actin cross-linking proteins with diverse functions. Besides regulating the actin cytoskeleton, they serve as important links between the extracellular matrix and the cytoskeleton by binding cell surface receptors, functioning as scaffolds for signaling proteins, and binding several other cytoskeletal proteins that regulate cell adhesion dynamics. Structurally, FLNs are formed of an amino terminal actin-binding domain followed by 24 immunoglobulin-like domains (IgFLNs). Recent studies have demonstrated that myosin-mediated contractile forces can reveal hidden protein binding sites in the domain pairs IgFLNa18-19 and 20-21, enabling FLNs to transduce me…
Insights into the catalytic mechanism of human sEH phosphatase by site-directed mutagenesis and LC-MS/MS analysis
2008
We have recently reported that human soluble epoxide hydrolase (sEH) is a bifunctional enzyme with a novel phosphatase enzymatic activity. Based on a structural relationship with other members of the haloacid dehalogenase superfamily, the sEH N-terminal phosphatase domain revealed four conserved sequence motifs, including the proposed catalytic nucleophile D9, and several other residues potentially implicated in substrate turnover and/or Mg(2+) binding. To enlighten the catalytic mechanism of dephosphorylation, we constructed sEH phosphatase active-site mutants by site-directed mutagenesis. A total of 18 mutants were constructed and recombinantly expressed in Escherichia coli as soluble pro…
Identification of a novel activating mutation (Y842C) within the activation loop of FLT3 in patients with acute myeloid leukemia (AML).
2004
Fms-like tyrosine kinase 3 (FLT3) receptor mutations as internal tandem duplication (ITD) or within the kinase domain are detected in up to 35% of patients with acute myeloid leukemia (AML). N-benzoyl staurosporine (PKC412), a highly effective inhibitor of mutated FLT3 receptors, has significant antileukemic efficacy in patients with FLT3-mutated AML. Mutation screening of FLT3 exon 20 in AML patients (n = 110) revealed 2 patients with a novel mutation (Y842C) within the highly conserved activation loop of FLT3. FLT3-Y842C-transfected 32D cells showed constitutive FLT3 tyrosine phosphorylation and interleukin 3 (IL-3)-independent growth. Treatment with PKC412 led to inhibition of proliferat…
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…
Photoinduced intersystem crossing in DNA oxidative lesions and epigenetic intermediates
2020
[EN] The propensity of 5-formyluracil and 5-formylcytosine, i.e. oxidative lesions and epigenetic intermediates, in acting as intrinsic DNA photosensitizers is unraveled by using a combination of molecular modeling, simulation and spectroscopy. Exploration of potential energy surfaces and non-adiabatic dynamics confirm a higher intersystem crossing rate for 5-formyluracil, whereas the kinetic models evidence different equilibria in the excited states for both compounds.
Unusual Formation of a Stable 2D Copper Porphyrin Network
2013
Copper(II) 5,15-bis(diethoxyphosphoryl)-10,20-diphenylporphyrin was obtained and characterized by means of cyclic voltammetry, electron paramagnetic resonance, Fourier transform infrared, and UV-visible spectroscopy. Three crystalline forms were grown and studied by means of X-ray diffraction methods (single crystal and powder). The highly electron-withdrawing effect of phosphoryl groups attached directly to the porphyrin macrocycle results in a self-assembling process, with formation of a stable 2D coordination network, which is unusual for copper(II) porphyrins. The resulting 2D structure is a rare example of an assembly based on copper(II) porphyrins where the copper(II) central metal io…
The regulation mechanism for the auto-inhibition of binding of human filamin A to integrin.
2009
The ability of adhesion receptors to transmit biochemical signals and mechanical force across cell membranes depends on interactions with the actin cytoskeleton. Human filamins are large actin cross-linking proteins that connect integrins to the cytoskeleton. Filamin binding to the cytoplasmic tail of beta integrins has been shown to prevent integrin activation in cells, which is important for controlling cell adhesion and migration. The molecular-level mechanism for filamin binding to integrin has been unclear, however, as it was recently demonstrated that filamin undergoes intramolecular auto-inhibition of integrin binding. In this study, using steered molecular dynamics simulations, we f…
Structure-based analyses of Salmonella RcsB variants unravel new features of the Rcs regulon
2021
18 páginas, 7 figuras, 2 tablas
Synthesis and antiproliferative activity of new derivatives containing the polycyclic system 5,7:7,13-dimethanopyrazolo[3,4-b]pyrazolo[3’,4’:2,3]azep…
2013
The reaction under reflux between 1-phenyl-3-R-5-methylaminopyrazoles and 2,5-hexanedione lead to 5,7:7,13-dimethanopyrazolo[3,4-b]pyrazolo[3′,4′:2,3]azepino[4,5-f]azocine derivatives 3b–g. These unusual molecules show the structural complexity of many biologically active natural products and are endowed with the chemical diversity that is required in drug discovery. The compounds 3b,e were reduced by hydrogen in the presence of Palladium on activated charcoal to give the dihydro derivatives 5b,e. Compounds 3b–f and 5b,e were selected by the NCI to evaluate their in vitro antiproliferative activity against 60 human cell lines derived from nine clinically isolated cancer types (leukaemia, lu…