Nonfouling NTA-PEG-Based TEM Grid Coatings for Selective Capture of Histidine-Tagged Protein Targets from Cell Lysates

Langmuir. 2016 Jan 19;32(2):551-9. doi: 10.1021/acs.langmuir.5b03445. Epub 2016 Jan 4.

Abstract

We report the preparation and performance of TEM grids bearing stabilized nonfouling lipid monolayer coatings. These films contain NTA capture ligands of controllable areal density at the distal end of a flexible poly(ethylene glycol) 2000 (PEG2000) spacer to avoid preferred orientation of surface-bound histidine-tagged (His-tag) protein targets. Langmuir-Schaefer deposition at 30 mN/m of mixed monolayers containing two novel synthetic lipids-1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[(5-amido-1-carboxypentyl)iminodiacetic acid]polyethylene glycolamide 2000) (NTA-PEG2000-DSPE) and 1,2-(tricosa-10',12'-diynoyl)-sn-glycero-3-phosphoethanolamine-N-(methoxypolyethylene glycolamide 350) (mPEG350-DTPE)-in 1:99 and 5:95 molar ratios prior to treatment with a 5 min, 254 nm light exposure was used for grid fabrication. These conditions were designed to limit nonspecific protein adsorption onto the stabilized lipid coating by favoring the formation of a mPEG350 brush layer below a flexible, mushroom conformation of NTA-PEG2000 at low surface density to enable specific immobilization and random orientation of the protein target on the EM grid. These grids were then used to capture His6-T7 bacteriophage and RplL from cell lysates, as well as purified His8-green fluorescent protein (GFP) and nanodisc solubilized maltose transporter, His6-MalFGK2. Our findings indicate that TEM grid supported, polymerized NTA lipid monolayers are capable of capturing His-tag protein targets in a manner that controls their areal densities, while efficiently blocking nonspecific adsorption and limiting film degradation, even upon prolonged detergent exposure.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • ATP-Binding Cassette Transporters / chemistry
  • ATP-Binding Cassette Transporters / genetics
  • Adsorption
  • Bacteriophage T7 / chemistry
  • Cell Extracts / chemistry
  • Cryoelectron Microscopy / instrumentation*
  • Escherichia coli / chemistry
  • Escherichia coli Proteins / chemistry
  • Escherichia coli Proteins / genetics
  • Gene Expression
  • Green Fluorescent Proteins / chemistry
  • Green Fluorescent Proteins / genetics
  • Histidine / chemistry*
  • Histidine / genetics
  • Microscopy, Electron, Transmission / instrumentation
  • Nitrilotriacetic Acid / chemistry*
  • Oligopeptides / chemistry*
  • Oligopeptides / genetics
  • Phosphatidylethanolamines / chemistry*
  • Polyethylene Glycols / chemistry*
  • Recombinant Fusion Proteins / chemistry*
  • Recombinant Fusion Proteins / genetics
  • Ribosomal Proteins / chemistry
  • Ribosomal Proteins / genetics
  • Surface Properties

Substances

  • 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-methoxy-poly(ethylene glycol 2000)
  • ATP-Binding Cassette Transporters
  • Cell Extracts
  • Escherichia coli Proteins
  • His-His-His-His-His-His
  • MPEG350
  • Oligopeptides
  • Phosphatidylethanolamines
  • Recombinant Fusion Proteins
  • Ribosomal Proteins
  • maltose transport system, E coli
  • Green Fluorescent Proteins
  • Polyethylene Glycols
  • Histidine
  • ribosomal protein L7-L12
  • polyethylene glycol 2000
  • Nitrilotriacetic Acid