The race-specific elicitor AVR9 of the tomato pathogen Cladosporium fulvum: a cystine knot protein. Sequence-specific 1H NMR assignments, secondary structure and global fold of the protein

FEBS Lett. 1997 Mar 10;404(2-3):153-8. doi: 10.1016/s0014-5793(97)00117-8.


The secondary structure and global fold of the AVR9 elicitor protein of Cladosporium fulvum has been determined by 2D NMR and distance-geometry protocols. The protein consists of three anti-parallel strands forming a rigid region of beta-sheet. On the basis of the NMR-derived parameters and distance geometry calculations, it is evident that the AVR9 protein is structurally very homologuous to carboxy peptidase inhibitor (CPI) of which the X-ray structure is known. The AVR9 protein reveals the presence of a cystine knot, which consists of a ring formed by two disulfide bridges and the interconnecting backbone through which the third disulfide bridge penetrates. This structural motif is found in several small proteins such as proteinase inhibitors, ion channel blockers and growth factors. The implications of the structural relationship between AVR9 and other biologically active proteins are discussed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Cladosporium / metabolism*
  • Cystine
  • Fungal Proteins / biosynthesis
  • Fungal Proteins / chemistry*
  • Fungal Proteins / isolation & purification
  • Hydrogen
  • Lycopersicon esculentum / microbiology*
  • Magnetic Resonance Spectroscopy
  • Models, Structural
  • Molecular Sequence Data
  • Peptide Fragments / chemistry
  • Protein Folding*
  • Protein Structure, Secondary*
  • Recombinant Fusion Proteins / biosynthesis
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / isolation & purification


  • Fungal Proteins
  • Peptide Fragments
  • Recombinant Fusion Proteins
  • AVR9 protein, Cladosporium fulvum
  • Cystine
  • Hydrogen