Sensing Native Protein Solution Structures Using a Solid-state Nanopore: Unraveling the States of VEGF

Sci Rep. 2018 Jan 17;8(1):1017. doi: 10.1038/s41598-018-19332-y.

Abstract

Monitoring individual proteins in solution while simultaneously obtaining tertiary and quaternary structural information is challenging. In this study, translocation of the vascular endothelial growth factor (VEGF) protein through a solid-state nanopore (ssNP) produces distinct ion-current blockade amplitude levels and durations likely corresponding to monomer, dimer, and higher oligomeric states. Upon changing from a non-reducing to a reducing condition, ion-current blockage events from the monomeric state dominate, consistent with the expected reduction of the two inter-chain VEGF disulfide bonds. Cleavage by plasmin and application of either a positive or a negative NP bias results in nanopore signals corresponding either to the VEGF receptor recognition domain or to the heparin binding domain, accordingly. Interestingly, multi-level analysis of VEGF events reveals how individual domains affect their translocation pattern. Our study shows that careful characterization of ssNP results elucidates real-time structural information about the protein, thereby complementing classical techniques for structural analysis of proteins in solution with the added advantage of quantitative single-molecule resolution of native proteins.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Binding Sites
  • DNA / chemistry*
  • Electrochemical Techniques
  • Fibrinolysin / chemistry*
  • Humans
  • Models, Molecular
  • Nanopores / ultrastructure
  • Oxidation-Reduction
  • Phosphines / chemistry
  • Protein Binding
  • Protein Interaction Domains and Motifs
  • Protein Structure, Secondary
  • Protein Transport
  • Recombinant Proteins / chemistry
  • Vascular Endothelial Growth Factor A / chemistry*

Substances

  • Phosphines
  • Recombinant Proteins
  • VEGFA protein, human
  • Vascular Endothelial Growth Factor A
  • tris(2-carboxyethyl)phosphine
  • DNA
  • Fibrinolysin