Seasonal and pandemic-associated influenza strains cause highly contagious viral respiratory infections that can lead to severe illness and excess mortality. Here, we report on the optimization of our small-molecule inhibitor F0045(S) targeting the influenza hemagglutinin (HA) stem with our Sulfur-Fluoride Exchange (SuFEx) click chemistry-based high-throughput medicinal chemistry (HTMC) strategy. A combination of SuFEx- and amide-based lead molecule diversification and structure-guided design led to identification and validation of ultrapotent influenza fusion inhibitors with subnanomolar EC cellular antiviral activity against several influenza A group 1 strains.
View Article and Find Full Text PDFTo achieve global elimination of hepatitis C virus (HCV), an effective cross-genotype vaccine is needed. The HCV envelope glycoprotein E2 is the main target for neutralizing antibodies (nAbs), which aid in HCV clearance and protection. E2 is structurally flexible and functions in engaging host receptors.
View Article and Find Full Text PDFInfluenza hemagglutinin (HA) glycoprotein is the primary surface antigen targeted by the host immune response and a focus for development of novel vaccines, broadly neutralizing antibodies (bnAbs), and therapeutics. HA enables viral entry into host cells via receptor binding and membrane fusion and is a validated target for drug discovery. However, to date, only a very few bona fide small molecules have been reported against the HA.
View Article and Find Full Text PDFRecent characterization of broadly neutralizing antibodies (bnAbs) against influenza virus identified the conserved hemagglutinin (HA) stem as a target for development of universal vaccines and therapeutics. Although several stem bnAbs are being evaluated in clinical trials, antibodies are generally unsuited for oral delivery. Guided by structural knowledge of the interactions and mechanism of anti-stem bnAb CR6261, we selected and optimized small molecules that mimic the bnAb functionality.
View Article and Find Full Text PDFThe influenza virus hemagglutinin (HA) glycoprotein mediates receptor binding and membrane fusion during viral entry in host cells. Blocking these key steps in viral infection has applications for development of novel antiinfluenza therapeutics as well as vaccines. However, the lack of structural information on how small molecules can gain a foothold in the small, shallow receptor-binding site (RBS) has hindered drug design against this important target on the viral pathogen.
View Article and Find Full Text PDFInfluenza therapeutics with new targets and mechanisms of action are urgently needed to combat potential pandemics, emerging viruses, and constantly mutating strains in circulation. We report here on the design and structural characterization of potent peptidic inhibitors of influenza hemagglutinin. The peptide design was based on complementarity-determining region loops of human broadly neutralizing antibodies against the hemagglutinin (FI6v3 and CR9114).
View Article and Find Full Text PDFInfluenza is a highly contagious respiratory viral infection responsible for up to 50,000 deaths per annum in the US alone. The need for new therapeutics with novel modes of action is of paramount importance. We determined the X-ray structure of Arbidol with influenza hemagglutinin and found it was located in a distinct binding pocket.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
January 2017
The broad-spectrum antiviral drug Arbidol shows efficacy against influenza viruses by targeting the hemagglutinin (HA) fusion machinery. However, the structural basis of the mechanism underlying fusion inhibition by Arbidol has remained obscure, thereby hindering its further development as a specific and optimized influenza therapeutic. We determined crystal structures of Arbidol in complex with influenza virus HA from pandemic 1968 H3N2 and recent 2013 H7N9 viruses.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
November 2016
Hepatitis C virus (HCV) is a major cause of liver disease, affecting over 2% of the world's population. The HCV envelope glycoproteins E1 and E2 mediate viral entry, with E2 being the main target of neutralizing antibody responses. Structural investigations of E2 have produced templates for vaccine design, including the conserved CD81 receptor-binding site (CD81bs) that is a key target of broadly neutralizing antibodies (bNAbs).
View Article and Find Full Text PDFHepatitis C virus (HCV) is a positive-strand RNA virus within the Flaviviridae family. The viral "spike" of HCV is formed by two envelope glycoproteins, E1 and E2, which together mediate viral entry by engaging host receptors and undergoing conformational changes to facilitate membrane fusion. While E2 can be readily produced in the absence of E1, E1 cannot be expressed without E2 and few reagents, including monoclonal antibodies (mAbs), are available for study of this essential HCV glycoprotein.
View Article and Find Full Text PDFThe galactopeptide dendrimer GalAG2 ((β-Gal-OC6H4CO-Lys-Pro-Leu)4(Lys-Phe-Lys-Ile)2Lys-His-Ile-NH2) binds strongly to the Pseudomonas aeruginosa (PA) lectin LecA, and it inhibits PA biofilms, as well as disperses already established ones. By starting with the crystal structure of the terminal tripeptide moiety GalA-KPL in complex with LecA, a computational mutagenesis study was carried out on the galactotripeptide to optimize the peptide-lectin interactions. 25 mutants were experimentally evaluated by a hemagglutination inhibition assay, 17 by isothermal titration calorimetry, and 3 by X-ray crystallography.
View Article and Find Full Text PDFHepatitis C virus (HCV), a Hepacivirus, is a major cause of viral hepatitis, liver cirrhosis, and hepatocellular carcinoma. HCV envelope glycoproteins E1 and E2 mediate fusion and entry into host cells and are the primary targets of the humoral immune response. The crystal structure of the E2 core bound to broadly neutralizing antibody AR3C at 2.
View Article and Find Full Text PDFApproximately 50% of cell wall peptidoglycan in Gram-negative bacteria is recycled with each generation. The primary substrates used for peptidoglycan biosynthesis and recycling in the cytoplasm are GlcNAc-MurNAc(anhydro)-tetrapeptide and its degradation product, the free tetrapeptide. This complex process involves ∼15 proteins, among which the cytoplasmic enzyme ld-carboxypeptidase A (LdcA) catabolizes the bond between the last two l- and d-amino acid residues in the tetrapeptide to form the tripeptide, which is then utilized as a substrate by murein peptide ligase (Mpl).
View Article and Find Full Text PDFThe galactose specific lectin LecA mediates biofilm formation in the opportunistic pathogen P. aeruginosa . The interaction between LecA and aromatic β-galactoside biofilm inhibitors involves an intermolecular CH-π T-shape interaction between C(ε1)-H of residue His50 in LecA and the aromatic ring of the galactoside aglycone.
View Article and Find Full Text PDFNorbornapeptides (bicyclo[2.2.1]heptapeptides) and related bicyclic homodetic peptides were prepared by solid-phase peptide synthesis using an orthogonal protection scheme.
View Article and Find Full Text PDFThe third-generation peptide-dendrimer B1 (AcES)8(BEA)4(K-Amb-Y)2BCD-NH2 (B=branching (S)-2,3-diaminopropanoic acid, K=branching lysine, Amb=4-aminomethyl-benzoic acid) is the first synthetic model for cobalamin-binding proteins and binds cobalamin strongly (K(a)=5.0 x 10(6) M(-1)) and rapidly (k(2)=346 M(-1) s(-1)) by coordination of cobalt to the cysteine residue at the dendrimer core. A structure-activity relationship study is reported concerning the role of negative charges in binding.
View Article and Find Full Text PDFThe fucose-specific lectin LecB is implicated in tissue binding and biofilm formation by the opportunistic pathogen Pseudomonas aeruginosa, which causes severe respiratory tract infections mainly in immunocompromised patients or cancer patients undergoing chemotherapy. With a view to developing multivalent LecB inhibitors as novel antibacterial agents, a combinatorial library containing 15 625 tetravalent C-fucosyl peptide dendrimers with the basic structure (CFuc-X(6)X(5)X(4))(4)(LysX(3)X(2)X(1))(2)LysIleHisNH(2) (CFuc=alpha-L-fucosyl acetic acid, X(1-6)=amino acids, Lys=lysine branching) was screened for lectin binding using on-bead binding assays. Ten tetravalent and three octavalent dendrimers derived from the identified sequences were prepared by solid-phase peptide synthesis (SPPS), cleaved from the resin, and purified by preparative HPLC.
View Article and Find Full Text PDFThe human pathogenic bacterium Pseudomonas aeruginosa produces a fucose-specific lectin, LecB, implicated in tissue attachment and the formation of biofilms. To investigate if LecB inhibition disrupts these processes, high-affinity ligands were obtained by screening two 15,536-member combinatorial libraries of multivalent fucosyl-peptide dendrimers. The most potent LecB-ligands identified were dendrimers FD2 (C-Fuc-LysProLeu)(4)(LysPheLysIle)(2)LysHisIleNH(2) (IC(50) = 0.
View Article and Find Full Text PDFDesign and development of therapeutically useful CNS selective thyrotropin-releasing hormone (TRH) analogs acting on TRH-R2 receptor subtype, exerting weak or no TRH-R1-mediated TSH-releasing side effects has gained imagination of researchers in the recent past. The present study reports the development and implementation of a selectivity-based QSAR approach for screening selective agonists of TRH-R2 receptor subtype. The statistically significant predictive models were thoroughly validated using an external validation set whose activity was previously unknown.
View Article and Find Full Text PDFNovel anti-leishmanial target LmSir2 has few subtle but prudent structural differences in ligand binding and catalytic domain as compared to its human counterpart. In silico screening and validation followed by in vitro deacetylation and cell killing assays described herein give a proof of concept for development of strategies exploiting such minor differences for screening libraries of small molecules to identify selective inhibitors.
View Article and Find Full Text PDFUDP-3-O-[R-3-hydroxymyristoyl]-GlcNAc deacetylase enzyme of Pseudomonas aeruginosa is an interesting target for development of anti-infective drugs against this gram-negative bacterium. Many segregated studies analyzing the P. aeruginosa UDP-3-O-[R-3-hydroxymyristoyl]-GlcNAc deacetylase and its inhibitors have been reported in the recent past.
View Article and Find Full Text PDFThe target for the anti-inflammatory natural products like amentoflavone ( 2), which act by interfering with the proinflammatory cytokine pathway (e.g., TNF-alpha, IL-1beta, and NO synthase), is not yet well-defined.
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