Schwartz, S.; Engstler, C.; Muehlbauer, S.; Windenbach, E.; Wunder, T.; Kunz, H.-H.; Brandt, B.

The purification of proteins is the foundation to study their structure, function, biochemical properties, and interaction partners. In plant research, unique challenges arise from the complexity of plant tissues, interference of secondary metabolites, and sometimes the low abundance of target proteins. Many conventional plant protein purification methods rely on expensive reagents, multi-step procedures, and labor-intensive workflows, limiting their feasibility for many applications. Here, we present the Catch & Release system, a cost-effective, fast and reliable one-step purification workflow for the isolation of soluble and membrane-bound proteins from plant tissues. The Catch & Release toolbox includes a vector set, a homemade GFP-trap and homemade proteases. Catch & Release vectors streamline cloning and transgenic plant selection through the Fluorescence-Accumulating Seed Technology (FAST), which marks positive transformants with a strongly fluorescing seed coat. Each plasmid consists of four, easy to exchange, modules: a plant promoter, a cloning dropout marker, protease cleavage sites, and seven different epitope tags, including an innovative dual-fluorescent tag, providing flexibility for diverse experimental needs. The in vivo functionality of all modules has been confirmed. Besides enabling standard molecular biological experimentation, our vector set in combination with homemade GFP-trap and proteases enables efficient and rapid isolation of soluble and high molecular weight membrane proteins directly from plants. By following our detailed reagent preparation instructions, purification costs can be decreased hundred-fold compared to the commercially available options.