Immobilization of His-tagged proteins on nickel-chelating nanolipoprotein particles

Nanolipoprotein particles (NLPs) are nanometer-sized, discoidal particles that self-assemble from purified apolipoprotein and phospholipid. Their size and facile functionalization suggest potential application of NLPs as platforms for the presentation and delivery of recombinant proteins. To this end, we investigated incorporation of nickel-chelating lipids into NLPs (NiNLPs) and subsequent sequestration of polyhistidine (His)-tagged proteins. From initial lipid screens for NLP formation, the two phospholipids DMPC and DOPC were identified as suitable bulk lipids for incorporation of the nickel-chelating lipid DOGS-NTA-Ni into NLPs, and NiNLPs were successfully formed with varying amounts of DOGS-NTA-Ni. NiNLPs consisting of 10% DOGS-NTA-Ni with 90% bulk lipid (either DMPC or DOPC) were thoroughly characterized by size exclusion chromatography (SEC), non-denaturing gradient gel electrophoresis (NDGGE), and atomic force microscopy (AFM). Three different His-tagged proteins were sequestered on NiNLPs in a nickel-dependent manner, and the amount of immobilized protein was contingent on the size and composition of the NiNLP.