Ideal for low-expressing protein targets, the LOBSTR E. coli expression strain allows for one-step polyhistidine-tag affinity purification by eliminating the two major E. coli contaminants.
Traditionally, a major drawback to using polyhistidine-tag affinity purification for proteins expressed in E. coli is contamination resulting from the presence of two naturally histidine-rich proteins in E. coli, ArnA and SlyD. LOBSTR (low background strain) is an E. coli strain for the expression of recombinant polyhistidine-tagged proteins that addresses this challenge.
LOBSTR maintains normal cell growth, but significantly reduces the polyhistidine-tag binding affinities of ArnA and SlyD. The strain therefore reduces contamination by those two proteins, yielding recombinant polyhistidine-tagged protein of higher purity. This allows for one-step purification of low-expressing recombinant proteins.
LOBSTR is based on BL21(DE3) and can be used like other commercially available competent cells. A BL21(DE3)-RIL version is also available, which contains extra copies of the argU, ileY, and leuW tRNA genes, as well as a chloramphenicol marker.