One-step production of bioactive human lipopolysaccharide binding protein from LPS-eliminated E. coli.

Human lipopolysaccharide (LPS) binding protein (LBP) is a ∼60 kDa glycosylated protein that mediates potent innate immune against invading Gram-negative bacteria by recognition of LPS in their outer membranes. To date, there is no method for efficient production of bioactive LPS-free LBP at sufficient amounts through prokaryotic expression system. Here we present a simple approach for rapid preparation of human LBP from a LPS-eliminated E. coli strain named ClearColi BL21 (DE)3. Combined with the usage of an ultra-high-affinity CL7/Im7 purification system, we achieved one-step purification of recombinant human LBP with over 90% purity at a yield of ∼4 mg/L when using LB culture medium. The produced LBP retains full LPS binding activity which was validated by fluorescence spectroscopy and isothermal titration calorimetry (ITC). Collectively, we develop a valid method that can be applied to cost-effectively produce and purify LPS-free proteins.