IMACulate(DE3), an E. coli Strain for High Purity His-Tagged Protein Purifications

Immobilised Metal Affinity Chromatography (IMAC) is widely used to purify his-tagged recombinant proteins from Escherichia coli. However, endogenous contaminants with histidine clusters, such as GFAT and PDH E1 proteins, are often co-purified with the target protein. The low background strain LOBSTR-RIL has been previously engineered with mutated forms of SlyD and ArnA that exhibit reduced binding to Ni²⁺ resin. In this study, the LOBSTR-RIL strain was further modified to produce IMACulate(DE3), where we altered the glmS (encoding GFAT protein) and aceE (encoding PDH E1 protein) genes to reduce surface histidines. Proteins purified from this strain show reduced levels of GFAT contamination. No statistically significant difference was observed in the abundance levels of PDH E1 protein in the BL21(DE3)-RIL, LOBSTR-RIL and IMACulate(DE3) strains. The use of IMACulate(DE3) increases the purity of recombinant his-tagged protein preparations with no additional effort or expense.