Fibronectin type III domains engineered to bind CD40L: cloning, expression, purification, crystallization and preliminary X-ray diffraction analysis of two complexes

Acta Crystallogr Sect F Struct Biol Cryst Commun. 2013 Sep;69(Pt 9):1045-8. doi: 10.1107/S1744309113022847. Epub 2013 Aug 21.


Tn3 proteins are a novel class of binding molecules based on the third fibronectin type III domain of human tenascin C. Target-specific Tn3 proteins are selected from combinatorial libraries in which three surface-exposed loops have been diversified. Here, the cocrystallization of two different Tn3 proteins in complex with CD40L, a therapeutic target for immunological disease, is reported. These crystal structures are the first to be reported of Tn3 proteins and will help to reveal how these engineered molecules achieve specific recognition of a cognate target.

Keywords: CD40L; fibronectin type III domains.

MeSH terms

  • Amino Acid Sequence
  • Binding Sites
  • CD40 Ligand / chemistry*
  • CD40 Ligand / genetics
  • CD40 Ligand / isolation & purification
  • Crystallography, X-Ray
  • Escherichia coli / genetics
  • Fibronectins / chemistry*
  • Fibronectins / genetics
  • Gene Expression
  • Humans
  • Molecular Sequence Data
  • Peptide Library
  • Peptides / chemistry*
  • Peptides / genetics
  • Peptides / isolation & purification
  • Protein Binding
  • Protein Structure, Secondary
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / genetics
  • Recombinant Proteins / isolation & purification
  • Sequence Alignment


  • Fibronectins
  • Peptide Library
  • Peptides
  • Recombinant Proteins
  • CD40 Ligand