Early Molecular Insights into Thanatin Analogues Binding to LptA.

The cationic antimicrobial ß-hairpin, thanatin, was recently developed into drug-like analogues active against carbapenem-resistant Enterobacteriaceae (CRE). The analogues represent new antibiotics with a novel mode of action targeting LptA in the periplasm and disrupting LPS transport. The compounds lose antimicrobial efficacy when the sequence identity to LptA falls below 70%.

Peptidomimetic antibiotics disrupt the lipopolysaccharide transport bridge of drug-resistant Enterobacteriaceae.

The rise of antimicrobial resistance poses a substantial threat to our health system, and, hence, development of drugs against novel targets is urgently needed. The natural peptide thanatin kills Gram-negative bacteria by targeting proteins of the lipopolysaccharide transport (Lpt) machinery. Using the thanatin scaffold together with phenotypic medicinal chemistry, structural data, and a target-focused approach, we developed antimicrobial peptides with drug-like properties.

Discovery of a small molecule ligand of FRS2 that inhibits invasion and tumor growth.

Purpose: Aberrant activation of the fibroblast growth factor receptor (FGFR) family of receptor tyrosine kinases drives oncogenic signaling through its proximal adaptor protein FRS2. Precise disruption of this disease-causing signal transmission in metastatic cancers could stall tumor growth and progression. The purpose of this study was to identify a small molecule ligand of FRS2 to interrupt oncogenic signal transmission from activated FGFRs.

Peptides in BioNMR Research.

Heteronuclear NMR in combination with isotope labelling is used to study folding of polypeptides induced by metals in the case of metallothioneins, binding of the peptidic allosteric modulator ρ-TIA to the human G-protein coupled α adrenergic receptor, the development of therapeutic drugs that interfere with the biosynthesis of the outer membrane of Gram-negative bacteria, and a system in which protein assembly is induced upon peptide addition. NMR in these cases is used to derive precise structural data and to study the dynamics.

An epitope-specific chemically defined nanoparticle vaccine for respiratory syncytial virus.

Respiratory syncytial virus (RSV) can cause severe respiratory disease in humans, particularly in infants and the elderly. However, attempts to develop a safe and effective vaccine have so far been unsuccessful. Atomic-level structures of epitopes targeted by RSV-neutralizing antibodies are now known, including that bound by Motavizumab and its clinically used progenitor Palivizumab.

Author Correction: Chimeric peptidomimetic antibiotics against Gram-negative bacteria.

An Amendment to this paper has been published and can be accessed via a link at the top of the paper.

Chimeric peptidomimetic antibiotics against Gram-negative bacteria.

There is an urgent need for new antibiotics against Gram-negative pathogens that are resistant to carbapenem and third-generation cephalosporins, against which antibiotics of last resort have lost most of their efficacy. Here we describe a class of synthetic antibiotics inspired by scaffolds derived from natural products. These chimeric antibiotics contain a β-hairpin peptide macrocycle linked to the macrocycle found in the polymyxin and colistin family of natural products.

Thanatin targets the intermembrane protein complex required for lipopolysaccharide transport in .

With the increasing resistance of many Gram-negative bacteria to existing classes of antibiotics, identifying new paradigms in antimicrobial discovery is an important research priority. Of special interest are the proteins required for the biogenesis of the asymmetric Gram-negative bacterial outer membrane (OM). Seven Lpt proteins (LptA to LptG) associate in most Gram-negative bacteria to form a macromolecular complex spanning the entire envelope, which transports lipopolysaccharide (LPS) molecules from their site of assembly at the inner membrane to the cell surface, powered by adenosine 5'-triphosphate hydrolysis in the cytoplasm.

A Peptidomimetic Antibiotic Interacts with the Periplasmic Domain of LptD from Pseudomonas aeruginosa.

The outer membrane (OM) in Gram-negative bacteria is an asymmetric bilayer with mostly lipopolysaccharide (LPS) molecules in the outer leaflet. During OM biogenesis, new LPS molecules are transported from their site of assembly on the inner membrane to the OM by seven LPS transport proteins (LptA-G). The complex formed between the integral β-barrel OM protein LptD and the lipoprotein LptE is responsible for transporting LPS from the periplasmic side of the OM to its final location on the cell surface.

Protein Epitope Mimetics: From New Antibiotics to Supramolecular Synthetic Vaccines.

Protein epitope mimetics provide powerful tools to study biomolecular recognition in many areas of chemical biology. They may also provide access to new biologically active molecules and potentially to new classes of drug and vaccine candidates. Here we highlight approaches for the design of folded, structurally defined epitope mimetics, by incorporating backbone and side chains of hot residues onto a stable constrained scaffold.

Protein epitope mimetic macrocycles as biopharmaceuticals.

Fully synthetic medium-sized macrocyclic peptides mimicking the key β-hairpin and α-helical protein epitopes relevant in many protein-protein interactions have emerged as a novel class of drugs with the potential to fill an important gap between small molecules and proteins. Conformationally stabilized macrocyclic scaffolds represent ideal templates for medicinal chemists to incorporate bioactive peptide and protein pharmacophores in order to generate novel drugs to treat diseases with high unmet medical need. This review describes recent approaches to design and generate large libraries of such macrocycles, for hit identification, and for their efficient optimization.

Synthesis and antimicrobial activity against Pseudomonas aeruginosa of macrocyclic β-hairpin peptidomimetic antibiotics containing N-methylated amino acids.

Antimicrobial resistance among Gram-negative bacteria is a growing problem, fueled by the paucity of new antibiotics that target these microorganisms. One novel family of macrocyclic β-hairpin-shaped peptidomimetics was recently shown to act specifically against Pseudomonas spp. by a novel mechanism of action, targeting the outer membrane protein LptD, which mediates lipopolysaccharide transport to the cell surface during outer membrane biogenesis.

Solution Structure and Dynamics of LptE from Pseudomonas aeruginosa.

LptE is an outer membrane (OM) lipoprotein found in Gram-negative bacteria, where it forms a complex with the β-barrel lipopolysaccharide (LPS) transporter LptD. The LptD/E complex plays a key role in OM biogenesis, by translocating newly synthesized LPS molecules from the periplasm into the external leaflet of the asymmetric OM during cell growth. The LptD/E complex in Pseudomonas aeruginosa (Pa) is a target for macrocyclic β-hairpin-shaped peptidomimetic antibiotics, which inhibit the transport of LPS to the cell surface.

A Peptidomimetic Antibiotic Targets Outer Membrane Proteins and Disrupts Selectively the Outer Membrane in Escherichia coli.

Increasing antibacterial resistance presents a major challenge in antibiotic discovery. One attractive target in Gram-negative bacteria is the unique asymmetric outer membrane (OM), which acts as a permeability barrier that protects the cell from external stresses, such as the presence of antibiotics. We describe a novel β-hairpin macrocyclic peptide JB-95 with potent antimicrobial activity against Escherichia coli.

Structural studies of β-hairpin peptidomimetic antibiotics that target LptD in Pseudomonas sp.

We report structural studies in aqueous solution on backbone cyclic peptides that possess potent antimicrobial activity specifically against Pseudomonas sp. The peptides target the β-barrel outer membrane protein LptD, which plays an essential role in lipopolysaccharide transport to the outer membrane. The peptide L27-11 contains a 12-residue loop (T(1)W(2)L(3)K(4)K(5)R(6)R(7)W(8)K(9)K(10)A(11)K(12)) linked to a DPro-LPro template.

Synthesis of a 6,6-spiroketal amino acid and its incorporation into a peptide turn sequence using solid-phase peptide synthesis.

Spiropins for SPPS: The rigid structure of an anomerically stabilised spiroketal motif enables the appendage of substituents in a fixed conformation. To assess the ability of a spiroketal motif to induce a turn structure and participate in solid-phase peptide synthesis (SPPS), an Fmoc-spiroketal amino acid was synthesised and incorporated into a spiroketal-containing cyclic peptide.

Synthetic virus-like particles and conformationally constrained peptidomimetics in vaccine design.

Conformationally constrained peptidomimetics could be of great value in the design of vaccines targeting protective epitopes on viral and bacterial pathogens. But the poor immunogenicity of small synthetic molecules represents a serious obstacle for their use in vaccine development. Here, we show how a constrained epitope mimetic can be rendered highly immunogenic through multivalent display on the surface of synthetic virus-like nanoparticles.

NMR studies of the solution conformation of the sex peptide from Drosophila melanogaster.

The insect sex peptide (SP) elicits a variety of biological responses upon transfer to the mated female. SP contains 36 amino acids, including a tryptophan-rich N-terminal region, a central region containing five hydroxyproline (Hyp) residues, and a C-terminal region enclosed by a disulfide bridge. The solution structure of SP, studied here using NMR spectroscopy, includes a motif WPWN that adopts a type I β-turn in the N-terminal Trp-rich region.

Engineered synthetic virus-like particles and their use in vaccine delivery.

Engineered nanoparticles have been designed based on the self-assembling properties of synthetic coiled-coil lipopeptide building blocks. The presence of an isoleucine zipper within the lipopeptide together with the aggregating effects of an N-terminal lipid drives formation of 20-25 nm nanoparticles in solution. Biophysical studies support a model in which the lipid is buried in the centre of the nanoparticle, with 20-30 trimeric helical coiled-coil bundles radiating out into solution.

Peptidomimetic inhibitors targeting the CCR5-binding site on the human immunodeficiency virus type-1 gp120 glycoprotein complexed to CD4.

A helical tyrosine-sulfated epitope in CCR5 that is recognized by the human immunodeficiency virus type-1 envelope glycoprotein gp120 in its CD4-induced conformation can be mimicked structurally by a cyclic β-hairpin peptide containing two sulfated tyrosine residues at positions i and i + 2 along one β-strand.

The design, structures and therapeutic potential of protein epitope mimetics.

Using a biologically relevant peptide or protein structure as a starting point for lead identification represents one of the most powerful approaches in modern drug discovery. Here, we focus on the protein epitope mimetic (PEM) approach, where folded 3D structures of peptides and proteins are taken as starting points for the design of synthetic molecules that mimic key epitopes involved in protein-protein and protein-nucleic acid interactions. By transferring the epitope from a recombinant to a synthetic scaffold that can be produced by parallel combinatorial methods, it is possible to optimize target affinity and specificity as well as other drug-like ADMET properties.