Biology subjects

Grasemann, L.

Publications and source records attributed to Grasemann, L..

4 recordsLinked to original sources

bioRxiv2025

High-throughput cell-free profiling of SARS-CoV-2 RBD variants enables rapid and quantitative in vitro affinity landscape mapping

SARS-CoV-2 variants continue to threaten public health, necessitating the study of cumulative and epistatic effects of receptor-binding domain (RBD) mutations on antibody evasion. We present a high-throughput platform combining cell-free protein synthesis and microfluidics to quantify the affinity of a large number of RBD triplet mutants covering the evolutionary space between wild-type and Omicron against two therapeutic antibodies and one engineered binder. Using rapid in vitro gene assembly and cell-free synthesis, we expressed 518 RBD variants and obtained 31,740 quantitative affinity measurements to generate three comprehensive binding energy landscapes. This approach enables rapid and large-scale in vitro affinity profiling and machine learning-based predictions, providing a valuable tool for studying emerging variants.

systems biology↗

bioRxiv2024

Long-term protein synthesis with PURE in a mesoscale dialysis system

Cell-free systems are powerful tools in synthetic biology with versatile and wide-ranging applications. However, a significant bottleneck for these systems, particularly the PURE cell-free system, is their limited reaction lifespan and yield. Dialysis offers a promising approach to prolong reaction lifetimes and increase yields, yet most custom dialysis systems require access to sophisticated equipment like 3D printers or microfabrication tools. In this study, we utilized an easy-to-assemble, medium-scale dialysis system for cell-free reactions using commercially available components. By employing dialysis with periodic exchange of the feeding solution, we achieved a protein yield of 1.16 mg/mL GFP in the PURE system and extended protein synthesis for at least 12.5 consecutive days, demonstrating the systems excellent stability.

synthetic biology↗

bioRxiv2023

C2CAplus: a one-pot isothermal circle-to-circle DNA amplification system

Rolling circle amplification (RCA) is a widely used DNA amplification method that uses circular template DNA as input and produces multimeric, linear single or double stranded DNA. Circle-to-circle amplification (C2CA) has further expanded this method by implementing product re-circularization using restriction and ligation, leading to a higher amplification yield, and enabling the generation of circular products. However, C2CA is a multistep, non-isothermal method, requiring multiple fluid manipulations and thereby compromises several advantages of RCA. Here, we improved C2CA to implement a one-pot, single step, isothermal reaction at temperatures ranging from 25 to 37{degrees}C. Our C2CAplus method is simple, robust, and produces large quantities of product DNA that can be seen with the naked eye.

synthetic biology↗

bioRxiv2022

Improved cell-free transcription-translation reactions in microfluidic chemostats augmented with hydrogel membranes for continuous small molecule dialysis

Increasing protein production capacity of the PURE cell-free transcription-translation (TX-TL) system will be key to implementing complex synthetic biological circuits, and to establish a fully self-regenerating system as a basis for the development of a synthetic cell. Under steady-state conditions, the protein synthesis capacity of the PURE system is likely at least one order of magnitude too low to express sufficient quantities of all PURE protein components. This is in part due to the fact that protein synthesis cant be sustained during the entire dilution cycle, especially at low dilution rates. We developed a microfluidic chemostat augmented with semi-permeable membranes that combines steady-state reactions and continuous dialysis as a possible solution to enhance protein synthesis at steady-state. In batch operation, the continuous dialysis of low molecular weight components via the membranes extended protein synthesis by over an order of magnitude from 2 hours to over 30 hours, leading to a seven-fold increase in protein yield. In chemostat operation, continuous dialysis enabled sustained protein synthesis during the entire dilution cycle even for low dilution rates, leading to six-fold higher protein levels at steady state. The possibility to combine and independently manipulate continuous dialysis and chemostat operation renders our dialysis chemostat a promising technological basis for complex cell-free synthetic biology applications that require enhanced protein synthesis capacity.

synthetic biology↗