The study of calmodulin (CaM) functions in living cells has been tackled up to date using cell-permeant CaM inhibitors or interference-RNA methods. CaM inhibitors may lack specificity and the siRNA interference approach is challenging, as all three CaM genes expressing an identical protein in mammals have to be blocked. Therefore, we recently introduced a novel genetic system using CRISPR/Cas9-mediated gene deletion and conditional CaM expression to study the function of CaM in HeLa cells. Here, we describe the effect of CaM downregulation on the basal and epidermal growth factor (EGF)-dependent 2D- and 3D-migration in HeLa cells. CaM downregulation inhibited cell migration on a 2D-surface in the absence but not in the presence of EGF. In contrast, CaM downregulation led to inhibition of 3D-migration across a porous membrane both in the absence and presence of EGF. CaM downregulation decreased the expression of Rac1, Cdc42 and RhoA, all known to play crucial roles in cell migration. These results show that EGF-dependent 2D- and 3D-migration utilize distinct CaM-regulated systems and identify several essential migratory proteins directly or indirectly regulated by CaM.We determined the crystal structure to 1.8 Å resolution of the Fab fragment of an affinity-matured human monoclonal antibody (HC84.26.5D) that recognizes the E2 envelope glycoprotein of hepatitis C virus (HCV). selleck chemicals Unlike conventional Fabs, which are monovalent monomers, Fab HC84.26.5D assembles into a bivalent domain-swapped dimer in which the two VL/VH modules are separated by ~25 Å. In solution, Fab HC84.26.5D exists predominantly as a dimer (~80%) in equilibrium with the monomeric form of the Fab (~20%). Dimerization is mediated entirely by deletion of a single residue, VHSer113 (Kabat numbering), in the elbow region linking the VH and CH1 domains. In agreement with the crystal structure, dimeric Fab HC84.26.5D is able to bind two HCV E2 molecules in solution. This is only the second example of a domain-swapped Fab dimer from among >3000 Fab crystal structures determined to date. Moreover, the architecture of the doughnut-shaped Fab HC84.26.5D dimer is completely different from that of the previously reported Fab 2G12 dimer. We demonstrate that the highly identifiable shape of dimeric Fab HC84.26.5D makes it useful as a fiducial marker for single-particle cryoEM analysis of HCV E2. Bivalent domain-swapped Fab dimers engineered on the basis of HC84.26.5D may also serve as a means of doubling the effective size of conventional Fab-protein complexes for cryoEM.The non-protein amino acid meta-Tyrosine (m-Tyr) is produced in cells under conditions of oxidative stress, and m-Tyr has been shown to be toxic to a broad range of biological systems. However, the mechanism by which m-Tyr damages cells is unclear. In E. coli, the quality control (QC) function of phenyalanyl-tRNA synthetase (PheRS) is required for resistantce to m-Tyr. To determine the mechanism of m-Tyr toxicity, we utilitized a strain of E. coli that expresses a QC-defective PheRS. The global responses of E. coli cells to m-Tyr were assessed by RNA-seq, and >500 genes were differentially expressed after the addition of m-Tyr. The most strongly up-regulated genes are involved in unfolded-protein stress response, and cells exposed to m-Tyr contained large, electron-dense protein aggregates, indicating that m-Tyr destabilized a large fraction of the proteome. Additionally, we observed that amino acid biosynthesis and transport regulons, controlled by ArgR, TrpR, and TyrR, and the stringent-response regulon, controlled by DksA/ppGpp, were differentially expressed. m-Tyr resistant mutants were isolated and found to have altered a promoter to increase expression of the enzymes for Phe production or to have altered transporters, which likely result in less uptake or increased efflux of m-Tyr. These findings indicate that when m-Tyr has passed the QC checkpoint by the PheRS, this toxicity of m-Tyr may result from interfering with amino acid metabolism, destabalizing a large number of proteins, and the formation of protein aggregates.Heat shock protein 90 (Hsp90) is a molecular chaperone that assists protein folding in an Adenosine triphosphate (ATP)-dependent way. Hsp90 has been reported to interact with Alzheimeŕs disease associated amyloid-β (Aβ) peptides and to suppress toxic oligomer- and fibril formation. However, the mechanism remains largely unclear. Here we use a combination of atomic force microscopy (AFM) imaging, circular dichroism (CD) spectroscopy and biochemical analysis to quantify this interaction and put forward a microscopic picture including rate constants for the different transitions towards fibrillation. We show that Hsp90 binds to Aβ40 monomers weakly but inhibits Aβ40 from growing into fibrils at substoichiometric concentrations. ATP impedes this interaction, presumably by modulating Hsp90’s conformational dynamics and reducing its hydrophobic surface. Altogether, these results might indicate alternative ways to prevent Aβ40 fibrillation by manipulating chaperones that are already abundant in the brain.Root-knot disease, caused by Meloidogyne spp., alters histology as well as physiology of the roots thus influencing metabolism of vegetative and reproductive parts leading to huge losses in crop productivity. The experimental plant, Vigna unguiculata L. (cowpea of Fabaceae family) var. Gomti is an economically important pulse crop plant. An experiment was conducted to evaluate the effects of different concentrations (0, 25, 50 or 100 ppm) and various modes of applications (root dip, soil drench or foliar spray) of MgO nanoparticles on cowpea infected with M. incognita. The MgO nanoparticles were synthesized chemically and characterized by transmission and scanning electron microscopy (TEM, SEM), UV-Vis spectroscopy, X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The scanning electron microscopy images of second stage juveniles of M. incognita treated with MgO nanoparticles (50 and 100 ppm) exhibited indentations, roughness and distortions in the cuticular surface, in comparison to the control untreated juveniles.