Host defence peptide plectasin targets bacterial cell wall precursor lipid II by a calcium-sensitive supramolecular mechanism.

Antimicrobial resistance is a leading cause of mortality, calling for the development of new antibiotics. The fungal antibiotic plectasin is a eukaryotic host defence peptide that blocks bacterial cell wall synthesis. Here, using a combination of solid-state nuclear magnetic resonance, atomic force microscopy and activity assays, we show that plectasin uses a calcium-sensitive supramolecular killing mechanism.

PepBiotics, novel cathelicidin-inspired antimicrobials to fight pulmonary bacterial infections.

Background: Antimicrobial peptides are considered potential alternatives to antibiotics. Here we describe the antibacterial properties of a family of novel cathelicidin-related (CR-) peptides, which we named PepBiotics, against bacteria typically present in cystic fibrosis (CF) patients.

Methods: Broth dilution assays were used to determine antibacterial activity of PepBiotics under physiological conditions, as well as development of bacterial resistance against these peptides.

Optimizing Exogenous Surfactant as a Pulmonary Delivery Vehicle for Chicken Cathelicidin-2.

The rising incidence of antibiotic-resistant lung infections has instigated a much-needed search for new therapeutic strategies. One proposed strategy is the use of exogenous surfactants to deliver antimicrobial peptides (AMPs), like CATH-2, to infected regions of the lung. CATH-2 can kill bacteria through a diverse range of antibacterial pathways and exogenous surfactant can improve pulmonary drug distribution.

Mode of action of teixobactins in cellular membranes.

The natural antibiotic teixobactin kills pathogenic bacteria without detectable resistance. The difficult synthesis and unfavourable solubility of teixobactin require modifications, yet insufficient knowledge on its binding mode impedes the hunt for superior analogues. Thus far, teixobactins are assumed to kill bacteria by binding to cognate cell wall precursors (Lipid II and III).

Design Parameters of Tissue-Engineering Scaffolds at the Atomic Scale.

Stem-cell behavior is regulated by the material properties of the surrounding extracellular matrix, which has important implications for the design of tissue-engineering scaffolds. However, our understanding of the material properties of stem-cell scaffolds is limited to nanoscopic-to-macroscopic length scales. Herein, a solid-state NMR approach is presented that provides atomic-scale information on complex stem-cell substrates at near physiological conditions and at natural isotope abundance.

Towards the Native Binding Modes of Antibiotics that Target Lipid II.

The alarming rise of antimicrobial resistance (AMR) imposes severe burdens on healthcare systems and the economy worldwide, urgently calling for the development of new antibiotics. Antimicrobial peptides could be ideal templates for next-generation antibiotics, due to their low propensity to cause resistance. An especially promising branch of antimicrobial peptides target lipid II, the precursor of the bacterial peptidoglycan network.

Shifts in the selectivity filter dynamics cause modal gating in K channels.

Spontaneous activity shifts at constant experimental conditions represent a widespread regulatory mechanism in ion channels. The molecular origins of these modal gating shifts are poorly understood. In the K channel KcsA, a multitude of fast activity shifts that emulate the native modal gating behaviour can be triggered by point-mutations in the hydrogen bonding network that controls the selectivity filter.

High-resolution NMR studies of antibiotics in cellular membranes.

The alarming rise of antimicrobial resistance requires antibiotics with unexploited mechanisms. Ideal templates could be antibiotics that target the peptidoglycan precursor lipid II, known as the bacterial Achilles heel, at an irreplaceable pyrophosphate group. Such antibiotics would kill multidrug-resistant pathogens at nanomolecular concentrations without causing antimicrobial resistance.

Elucidating Self-Assembling Peptide Aggregation via Morphoscanner: A New Tool for Protein-Peptide Structural Characterization.

Self-assembling and molecular folding are ubiquitous in Nature: they drive the organization of systems ranging from living creatures to DNA molecules. Elucidating the complex dynamics underlying these phenomena is of crucial importance. However, a tool for the analysis of the various phenomena involved in protein/peptide aggregation is still missing.

Collagen I derived recombinant protein microspheres as novel delivery vehicles for bone morphogenetic protein-2.

Bone morphogenetic protein-2 (BMP-2) is a powerful osteoinductive protein; however, there is a need for the development of a safe and efficient BMP-2 release system for bone regeneration therapies. Recombinant extracellular matrix proteins are promising next generation biomaterials since the proteins are well-defined, reproducible and can be tailored for specific applications. In this study, we have developed a novel and versatile BMP-2 delivery system using microspheres from a recombinant protein based on human collagen I (RCP).

Virus-Like Particles of mRNA with Artificial Minimal Coat Proteins: Particle Formation, Stability, and Transfection Efficiency.

RNA has enormous potential as a therapeutic, yet, the successful application depends on efficient delivery strategies. In this study, we demonstrate that a designed artificial viral coat protein, which self-assembles with DNA to form rod-shaped virus-like particles (VLPs), also encapsulates and protects mRNA encoding enhanced green fluorescent protein (EGFP) and luciferase, and yields cellular expression of these proteins. The artificial viral coat protein consists of an oligolysine (K) for binding to the oligonucleotide, a silk protein-like midblock S = (GAGAGAGQ) that self-assembles into stiff rods, and a long hydrophilic random coil block C that shields the nucleic acid cargo from its environment.

Hydrogen bond strength in membrane proteins probed by time-resolved H-detected solid-state NMR and MD simulations.

H-detected solid-state NMR in combination with H/D exchange steps allows for the direct identification of very strong hydrogen bonds in membrane proteins. On the example of the membrane-embedded potassium channel KcsA, we quantify the longevity of such very strong hydrogen bonds by combining time-resolved H-detected solid-state NMR experiments and molecular dynamics simulations. In particular, we show that the carboxyl-side chain of the highly conserved residue Glu51 is involved in ultra-strong hydrogen bonds, which are fully-water-exposed and yet stable for weeks.

H-Detected Solid-State NMR Studies of Water-Inaccessible Proteins In Vitro and In Situ.

H detection can significantly improve solid-state NMR spectral sensitivity and thereby allows studying more complex proteins. However, the common prerequisite for H detection is the introduction of exchangeable protons in otherwise deuterated proteins, which has thus far significantly hampered studies of partly water-inaccessible proteins, such as membrane proteins. Herein, we present an approach that enables high-resolution H-detected solid-state NMR (ssNMR) studies of water-inaccessible proteins, and that even works in highly complex environments such as cellular surfaces.