Chemical synthesis and X-ray structure of a heterochiral {D-protein antagonist plus vascular endothelial growth factor} protein complex by racemic crystallography

Proc Natl Acad Sci U S A. 2012 Sep 11;109(37):14779-84. doi: 10.1073/pnas.1210483109. Epub 2012 Aug 27.

Abstract

Total chemical synthesis was used to prepare the mirror image (D-protein) form of the angiogenic protein vascular endothelial growth factor (VEGF-A). Phage display against D-VEGF-A was used to screen designed libraries based on a unique small protein scaffold in order to identify a high affinity ligand. Chemically synthesized D- and L- forms of the protein ligand showed reciprocal chiral specificity in surface plasmon resonance binding experiments: The L-protein ligand bound only to D-VEGF-A, whereas the D-protein ligand bound only to L-VEGF-A. The D-protein ligand, but not the L-protein ligand, inhibited the binding of natural VEGF(165) to the VEGFR1 receptor. Racemic protein crystallography was used to determine the high resolution X-ray structure of the heterochiral complex consisting of {D-protein antagonist + L-protein form of VEGF-A}. Crystallization of a racemic mixture of these synthetic proteins in appropriate stoichiometry gave a racemic protein complex of more than 73 kDa containing six synthetic protein molecules. The structure of the complex was determined to a resolution of 1.6 Å. Detailed analysis of the interaction between the D-protein antagonist and the VEGF-A protein molecule showed that the binding interface comprised a contact surface area of approximately 800 Å(2) in accord with our design objectives, and that the D-protein antagonist binds to the same region of VEGF-A that interacts with VEGFR1-domain 2.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Bacterial Proteins / genetics
  • Chromatography, High Pressure Liquid
  • Circular Dichroism
  • Crystallography, X-Ray
  • Enzyme-Linked Immunosorbent Assay
  • Epitope Mapping
  • Ligands
  • Mass Spectrometry
  • Models, Molecular*
  • Molecular Sequence Data
  • Multiprotein Complexes / chemistry*
  • Multiprotein Complexes / metabolism
  • Open Reading Frames
  • Stereoisomerism
  • Surface Plasmon Resonance
  • Vascular Endothelial Growth Factor A / chemical synthesis*
  • Vascular Endothelial Growth Factor A / chemistry*
  • Vascular Endothelial Growth Factor A / genetics
  • Vascular Endothelial Growth Factor A / metabolism*

Substances

  • Bacterial Proteins
  • IgG Fc-binding protein, Streptococcus
  • Ligands
  • Multiprotein Complexes
  • Vascular Endothelial Growth Factor A

Associated data

  • PDB/4GLN
  • PDB/4GLS
  • PDB/4GLU