A Cell-free Expression Pipeline for the Generation and Functional Characterization of Nanobodies

Fast In Vitro Synthesis and Direct Labeling of Nanobodies for Prototyping in Microscopy Applications

Small antigen binders, such as nanobodies, have become widely used in biomedical research and pharmaceutical development. However, the pipeline for the generation of functional conjugated probes and drugs from identified binders remains a major time-consuming bottleneck. Here, we developed a method for fast nanobody production and conjugation based on an in vitro synthesis platform. Our system allows for small batch synthesis of nanobodies with the inclusion of a noncanonical amino acid (NCAA). This NCAA can then be used for direct conjugation of molecules to the synthesized nanobody using click-chemistry, reducing the time from binder-encoding DNA to a conjugated probe tremendously. In this study, we conjugated a fluorescent dye to an anti-Green fluorescent protein (GFP) nanobody and attained a fully functional probe suitable for advanced super-resolution microscopy within a short time frame of 2 days. Our work illustrates that an in vitro synthesis platform in combination with click-chemistry can be successfully employed to produce conjugated small antigen binding probes. The fast production and conjugation, combined with the possibility for parallelization as well as precise analysis by microscopy, forms an excellent platform for nanobody prototyping. The here-illustrated method can be used for quick selection and benchmarking of obtained nanobody sequences/clones, e. g., from a phage-display, for use as conjugated small-molecule carriers. This procedure can accelerate the bioengineering of nanobodies for research and pharmaceutical applications.

Synthesis of mono Cytochrome P450 in a modified CHO-CPR cell-free protein production platform

Cytochromes P450 (CYPs) are a group of monooxygenases that can be found in almost all kinds of organisms. For CYPs to receive electrons from co-substrate NADPH, the activity of NADPH-Cytochrome-P450-oxidoreductase (CPR) is required as well. In humans, CYPs are an integral part of liver-based phase-1 biotransformation, which is essential for the metabolization of multiple xenobiotics and drugs. Consequently, CYPs are important players during drug development and therefore these enzymes are implemented in diverse screening applications. For these applications it is usually advantageous to use mono CYP microsomes containing only the CYP of interest. The generation of mono-CYP containing mammalian cells and vesicles is difficult since endogenous CYPs are present in many cell types that contain the necessary co-factors. By obtaining translationally active lysates from a modified CHO-CPR cell line, it is now possible to generate mono CYPs in a cell-free protein synthesis process in a straightforward manner. As a proof of principle, the synthesis of active human CYPs from three different CYP450 gene families (CYP1A2, CYP2B6 and CYP3A4), which are of outstanding interest in industry and academia was demonstrated. Luciferase based activity assays confirm the activity of the produced CYPs and enable the individual adaptation of the synthesis process for efficient cell-free enzyme production. Furthermore, they allow for substrate and inhibitor screenings not only for wild-type CYPs but also for mutants and further CYP isoforms and variants. As an example, the turnover of selected CYP substrates by cell-free synthesized CYPs was demonstrated via an indirect luciferase assay-based screening setup.

State-of-the-Art Approaches to Heterologous Expression of Bispecific Antibodies Targeting Solid Tumors

Bispecific antibodies (bsAbs) are some of the most promising biotherapeutics due to the versatility provided by their structure and functional features. bsAbs simultaneously bind two antigens or two epitopes on the same antigen. Moreover, they are capable of directing immune effector cells to cancer cells and delivering various compounds (radionuclides, toxins, and immunologic agents) to the target cells, thus offering a broad spectrum of clinical applications. Current review is focused on the technologies used in bsAb engineering, current progress and prospects of these antibodies, and selection of various heterologous expression systems for bsAb production. We also discuss the platforms development of bsAbs for the therapy of solid tumors.