Dynamic Light-Induced Protein Patterns at Model Membranes.

The precise localization and activation of proteins at the cell membrane at a certain time gives rise to many cellular processes, including cell polarization, migration, and division. Thus, methods to recruit proteins to model membranes with subcellular resolution and high temporal control are essential when reproducing and controlling such processes in synthetic cells. Here, a method is described for fabricating light-regulated reversible protein patterns at lipid membranes with high spatiotemporal precision.

NTA-Cholesterol Analogue for the Nongenetic Liquid-Ordered Phase-Specific Functionalization of Lipid Membranes with Proteins.

The nongenetic modification of cell membranes with proteins is a straightforward way of cellular engineering. In these processes, it is important to specifically address the proteins to liquid-ordered (Lo) or liquid-disordered (Ld) domains as this can largely affect their biological functions. Herein, we report a cholesterol analogue (CHIM) with a nitrilotriacetic acid (NTA) headgroup, named CHIM-NTA.

A disordered tether to iLID improves photoswitchable protein patterning on model membranes.

Reversible protein patterning on model membranes is important to reproduce spatiotemporal protein dynamics . An engineered version of iLID, disiLID, with a disordered domain as a membrane tether improves the recruitment of Nano under blue light and the reversibility in the dark, which enables protein patterning on membranes with higher spatiotemporal precision.

hedgehog signaling range and robustness depend on direct and sustained heparan sulfate interactions.

Morphogens determine cellular differentiation in many developing tissues in a concentration dependent manner. As a central model for gradient formation during animal development, Hedgehog (Hh) morphogens spread away from their source to direct growth and pattern formation in the wing disc. Although heparan sulfate (HS) expression in the disc is essential for this process, it is not known whether HS regulates Hh signaling and spread in a direct or in an indirect manner.

Hedgehog is relayed through dynamic heparan sulfate interactions to shape its gradient.

Cellular differentiation is directly determined by concentration gradients of morphogens. As a central model for gradient formation during development, Hedgehog (Hh) morphogens spread away from their source to direct growth and pattern formation in Drosophila wing and eye discs. What is not known is how extracellular Hh spread is achieved and how it translates into precise gradients.

Towards applications of synthetic cells in nanotechnology.

Synthetic cells, which are assembled anew from well-defined molecular parts, open-up new possibilities for nanotechnological applications due to their reduced complexity and high functionality. In this review, we discuss how synthetic cells are being implemented in different fields ranging from biomedicine to material science. On one hand, synthetic cells can serve as microreactors that house metabolic networks and as therapeutic carriers that directly communicate with living cells.

Multivalent Noncovalent Interfacing and Cross-Linking of Supramolecular Tubes.

Natural supramolecular filaments have the ability to cross-link with each other and to interface with the cellular membrane via biomolecular noncovalent interactions. This behavior allows them to form complex networks within as well as outside the cell, i.e.

Generation and Characterization of a Polyclonal Human Reference Antibody to Measure Anti-Drug Antibody Titers in Patients with Fabry Disease.

Male patients with Fabry disease (FD) are at high risk for the formation of antibodies to recombinant α-galactosidase A (AGAL), used for enzyme replacement therapy. Due to the rapid disease progression, the identification of patients at risk is highly warranted. However, currently suitable references and standardized protocols for anti-drug antibodies (ADA) determination do not exist.

Hierarchical Multivalent Effects Control Influenza Host Specificity.

Understanding how emerging influenza viruses recognize host cells is critical in evaluating their zoonotic potential, pathogenicity, and transmissibility between humans. The surface of the influenza virus is covered with hemagglutinin (HA) proteins that can form multiple interactions with sialic acid-terminated glycans on the host cell surface. This multivalent binding affects the selectivity of the virus in ways that cannot be predicted from the individual receptor-ligand interactions alone.

"Plug-n-Play" Polymer Substrates: Surface Patterning with Reactive-Group-Appended Poly-l-lysine for Biomolecule Adhesion.

The immobilization of biomolecules onto polymeric surfaces employed in the fabrication of biomedical and biosensing devices is generally a challenging issue, as the absence of functional groups in such materials does not allow the use of common surface chemistries. Here we report the use of modified poly-l-lysine (PLL) as an effective method for the selective modification of polymeric materials with biomolecules. Cyclic olefin polymer (COP), Ormostamp, and polydimethylsiloxane (PDMS) surfaces were patterned with modified PLLs displaying either biotin or maleimide functional groups.

Influenza-induced thrombocytopenia is dependent on the subtype and sialoglycan receptor and increases with virus pathogenicity.

Thrombocytopenia is a common complication of influenza virus infection, and its severity predicts the clinical outcome of critically ill patients. The underlying cause(s) remain incompletely understood. In this study, in patients with an influenza A/H1N1 virus infection, viral load and platelet count correlated inversely during the acute infection phase.

Recruitment of receptors at supported lipid bilayers promoted by the multivalent binding of ligand-modified unilamellar vesicles.

The development of model systems that mimic biological interactions and allow the control of both receptor and ligand densities, is essential for a better understanding of biomolecular processes, such as the recruitment of receptors at interfaces, at the molecular level. Here we report a model system based on supported lipid bilayers (SLBs) for the investigation of the clustering of receptors at their interface. Biotinylated SLBs, used as cell membrane mimics, were functionalized with streptavidin (SAv), used here as receptor.

Surface Modification with Control over Ligand Density for the Study of Multivalent Biological Systems.

In the study of multivalent interactions at interfaces, as occur for example at cell membranes, the density of the ligands or receptors displayed at the interface plays a pivotal role, affecting both the overall binding affinities and the valencies involved in the interactions. In order to control the ligand density at the interface, several approaches have been developed, and they concern the functionalization of a wide range of materials. Here, different methods employed in the modification of surfaces with controlled densities of ligands are being reviewed.

Clickable poly-l-lysine for the formation of biorecognition surfaces.

Biomolecules are immobilized onto surfaces employing the fast and stable adsorption of poly-l-lysine (PLL) polymers and the versatile copper-free click chemistry reactions. This method provides the combined advantages of versatile surface adsorption with density control using polyelectrolytes and of the covalent and orthogonal immobilization of biomolecules with higher reaction rates and improved yields of click chemistry. Using DNA attachment as a proof of concept, control over the DNA probe density and applicability in electrochemical detection are presented.

Weak Multivalent Binding of Influenza Hemagglutinin Nanoparticles at a Sialoglycan-Functionalized Supported Lipid Bilayer.

Quantification of the multivalent interactions of influenza viruses binding at interfaces may provide ways to tackle key biological questions regarding influenza virulence and zoonoses. Yet, the deconvolution of the contributions of molecular and interfacial parameters, such as valency, interaction area, and receptor density, to the binding of whole viruses is hindered by difficulties in the direct determination of these parameters. We report here a chemical platform technology to study the binding of multivalent recombinant hemagglutinin (rHA) nanoparticles at artificial sialoglycan cell receptor-presenting interfaces in which all these parameters can be derived, thus allowing the desired full and quantitative binding analysis.