Control of Protein Function through Optochemical Translocation

Controlled manipulation of proteins and their function is important in almost all biological disciplines. Here, we demonstrate control of protein activity with light. We present two different applicationslight-triggered transcription and light-triggered protease cleavageboth based on the same concept of protein mislocation, followed by optochemically triggered translocation to an active cellular compartment. In our approach, we genetically encode a photocaged lysine into the nuclear localization signal (NLS) of the transcription factor SATB1. This blocks nuclear import of the protein until illumination induces caging group removal and release of the protein into the nucleus. In the first application, prepending this NLS to the transcription factor FOXO3 allows us to optochemically switch on its transcription activity. The second application uses the developed light-activated NLS to control nuclear import of TEV protease and subsequent cleavage of nuclear proteins containing TEV cleavage sites. The small size of the light-controlled NLS (only 20 amino acids) minimizes impact of its insertion on protein function and promises a general approach to a wide range of optochemical applications. Since the light-activated NLS is genetically encoded and optically triggered, it will prove useful to address a variety of problems requiring spatial and temporal control of protein function, for example, in stem-cell, developmental, and cancer biology

Control of Protein Function through Optochemical Translocation

Controlled manipulation of proteins and their function is important in almost all biological disciplines. Here, we demonstrate control of protein activity with light. We present two different applicationslight-triggered transcription and light-triggered protease cleavageboth based on the same concept of protein mislocation, followed by optochemically triggered translocation to an active cellular compartment. In our approach, we genetically encode a photocaged lysine into the nuclear localization signal (NLS) of the transcription factor SATB1. This blocks nuclear import of the protein until illumination induces caging group removal and release of the protein into the nucleus. In the first application, prepending this NLS to the transcription factor FOXO3 allows us to optochemically switch on its transcription activity. The second application uses the developed light-activated NLS to control nuclear import of TEV protease and subsequent cleavage of nuclear proteins containing TEV cleavage sites. The small size of the light-controlled NLS (only 20 amino acids) minimizes impact of its insertion on protein function and promises a general approach to a wide range of optochemical applications. Since the light-activated NLS is genetically encoded and optically triggered, it will prove useful to address a variety of problems requiring spatial and temporal control of protein function, for example, in stem-cell, developmental, and cancer biology

Control of Protein Function through Optochemical Translocation

Controlled manipulation of proteins and their function is important in almost all biological disciplines. Here, we demonstrate control of protein activity with light. We present two different applicationslight-triggered transcription and light-triggered protease cleavageboth based on the same concept of protein mislocation, followed by optochemically triggered translocation to an active cellular compartment. In our approach, we genetically encode a photocaged lysine into the nuclear localization signal (NLS) of the transcription factor SATB1. This blocks nuclear import of the protein until illumination induces caging group removal and release of the protein into the nucleus. In the first application, prepending this NLS to the transcription factor FOXO3 allows us to optochemically switch on its transcription activity. The second application uses the developed light-activated NLS to control nuclear import of TEV protease and subsequent cleavage of nuclear proteins containing TEV cleavage sites. The small size of the light-controlled NLS (only 20 amino acids) minimizes impact of its insertion on protein function and promises a general approach to a wide range of optochemical applications. Since the light-activated NLS is genetically encoded and optically triggered, it will prove useful to address a variety of problems requiring spatial and temporal control of protein function, for example, in stem-cell, developmental, and cancer biology

Clickable Multifunctional Large-Pore Mesoporous Silica Nanoparticles as Nanocarriers

Large-pore mesoporous silica nanoparticles (LP-MSNs) with defined particle size (<200 nm) are promising carrier systems for the cellular delivery of macromolecules. Ideal nanocarriers should be adaptable in their surface properties to optimize host–guest interactions; thus, surface functionalization of the nanovehicles is highly desirable. In this study, we synthesized various monofunctional LP-MSNs by incorporating different organic groups into the silica framework via a co-condensation approach. Further, we applied a delayed co-condensation strategy to create spatially segregated core–shell bifunctional LP-MSNs. Diverse particle morphologies were obtained by adding different organosilanes to the silica precursor solution. The effect of organosilanes in the co-condensation process on particle size and pore structure formation is also discussed. Surface functional groups were then used for binding stimuli-responsive linkers. These were finally exploited for copper-free click chemistry for cargo conjugation to create a delivery system with controlled cargo release. Model cargo release experiments in buffer using these new multifunctional LP-MSNs demonstrate their ability in controlled cargo uptake and release and their potential for biomolecule delivery

Imparting Functionality to MOF Nanoparticles by External Surface Selective Covalent Attachment of Polymers

Selective functionalization of the external surface of porous nanoparticles is of great interest for numerous potential applications in the field of nanotechnology. Regarding metal–organic frameworks (MOFs), few methods for such modifications have been reported in the literature. Herein, we focus on the covalent attachment of functional polymers on the external surface of MIL-100­(Fe) nanoparticles in order to implement properties such as increased chemical and colloidal stability or dye-labeling for the investigation of the particles by fluorescence based techniques. We prove covalent nanoparticles-polymer bond formation by liquid NMR after dissolution of the functionalized MOF under mild conditions and estimate the amount of covalently attached polymer by UV–vis spectroscopy. The functionalization of the MOF nanoparticles with fluorescently labeled polymers enables the investigation of nanoparticle uptake into tumor cells by fluorescence microscopy. Furthermore, the influence of the polymer shell on the magnetic resonance imaging activity of MIL-100­(Fe) is investigated in detail. The functionalization approach presented here is expected to enable the fabrication of hybrid nanomaterials, extending the enormous chemical space of MOFs into polymer materials

Coordinative Binding of Polymers to Metal–Organic Framework Nanoparticles for Control of Interactions at the Biointerface

Metal–organic framework nanoparticles (MOF NPs) are of growing interest in diagnostic and therapeutic applications, and due to their hybrid nature, they display enhanced properties compared to more established nanomaterials. The effective application of MOF NPs, however, is often hampered by limited control of their surface chemistry and understanding of their interactions at the biointerface. Using a surface coating approach, we found that coordinative polymer binding to Zr-fum NPs is a convenient way for peripheral surface functionalization. Different polymers with biomedical relevance were assessed for the ability to bind to the MOF surface. Carboxylic acid and amine containing polymers turned out to be potent surface coatings and a modulator replacement reaction was identified as the underlying mechanism. The strong binding of polycarboxylates was then used to shield the MOF surface with a double amphiphilic polyglutamate–polysarcosine block copolymer, which resulted in an exceptional high colloidal stability of the nanoparticles. The effect of polymer coating on interactions at the biointerface was tested with regard to cellular association and protein binding, which has, to the best of our knowledge, never been discussed in literature for functionalized MOF NPs. We conclude that the applied approach enables a high degree of chemical surface confinement, which could be used as a universal strategy for MOF NP functionalization. In this way, the physicochemical properties of MOF NPs could be tuned, which allows for control over their behavior in biological systems