Engineered dihydrofolate reductase (eDHFR)

Engineered dihydrofolate reductase (eDHFR) is a modified version of the DHFR enzyme, typically derived from Escherichia coli, that functions as a powerful chemogenetic tool in synthetic biology and gene therapy (Iwamoto et al., 2010, Chemistry & Biology). It is most commonly utilized as a destabilizing domain (DD); in this system, specific mutations render the protein fold inherently unstable, targeting it and any fused therapeutic protein for rapid proteasomal degradation (Selleck et al., 2019, Blood). The administration of a small-molecule stabilizer, such as the antibiotic trimethoprim (TMP), allows the ligand to bind the eDHFR domain, restoring its structural integrity and preventing degradation (Obsidian Therapeutics, 2023). This technology enables precise, dose-dependent control over the expression of therapeutic payloads, such as chimeric antigen receptors (CARs) or cytokines, providing a safety switch to manage toxicities like cytokine release syndrome (Sadelain et al., 2021, Nature Reviews Cancer). Additionally, eDHFR variants engineered with mutations like L22Y or F31G are used to confer resistance to methotrexate, serving as selectable markers or protective transgenes in chemotherapy (Ercikan-Abali et al., 1996, Cancer Research). While highly effective for temporal control of gene expression, the use of non-human eDHFR sequences poses a risk of immunogenicity, and the requirement for continuous ligand administration presents a logistical challenge in clinical settings (UniProt P0ABQ4).

Other names

ecDHFRDHFR destabilizing domainDHFR-DDMutant dihydrofolate reductase

The primary mechanism involves ligand-induced protein stabilization, where a small-molecule ligand (e.g., trimethoprim) binds to an engineered, unstable DHFR domain to prevent its proteasomal degradation (Iwamoto et al., 2010). Additionally, engineered variants can provide resistance to inhibitors like methotrexate by altering the active site to reduce drug affinity while preserving catalytic function (Ercikan-Abali et al., 1996).