Wheat Subtilisin/Chymotrypsin Inhibitor (WSCI) as a scaffold for novel serine protease inhibitors with a given specificity

Mol Biosyst. 2012 Oct 30;8(12):3335-43. doi: 10.1039/c2mb25320h.


WSCI (Wheat Subtilisin/Chymotrypsin Inhibitor) is a small protein belonging to the Potato inhibitor I family exhibiting a high content of essential amino acid. In addition to bacterial subtilisins and mammalian chymotrypsins, WSCI inhibits chymotrypsin-like activities isolated from digestive traits of a number of insect larvae. In vivo, as suggested for many plant proteinase inhibitors, WSCI seems to play a role of natural defence against attacks of pests and pathogens. The functional region of WSCI, containing the inhibitor reactive site (Met48-Glu49), corresponds to an extended flexible loop (Val42-Asp53) whose architecture is somehow stabilized by a number of secondary interactions established with a small β-sheet located underneath. The aim of this study was to employ a WSCI molecule as a stable scaffold to obtain recombinant inhibitors with new acquired anti-proteinase activity or, alternatively, inactive WSCI variants. A gene sequence coding for the native WSCI, along with genes coding for muteins with different specficities, could be exploited to obtain transformed non-food use plants with improved insect resistance. On the other hand, the genetic transformation of cereal plants over-expressing inactive WSCI muteins could represent a possible strategy to improve the nutritional quality of cereal-based foods, without risk of interference with human or animal digestive enzymes. Here, we described the characterization of four muteins containing single/multiple amino acid substitutions at the WSCI reactive site and/or at its proximity. Modalities of interaction of these muteins with proteinases (subtilisin, trypsin and chymotrypsin) were investigated by time course hydrolysis and molecular simulations studies.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Amino Acid Substitution
  • Animals
  • Catalytic Domain
  • Chymotrypsin / antagonists & inhibitors
  • Humans
  • Leukocyte Elastase / antagonists & inhibitors
  • Pancreatic Elastase / antagonists & inhibitors
  • Plant Proteins / chemistry*
  • Plant Proteins / genetics
  • Plant Proteins / metabolism*
  • Protein Engineering*
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / metabolism
  • Recombinant Proteins / pharmacology
  • Serine Proteinase Inhibitors / chemistry*
  • Serine Proteinase Inhibitors / metabolism*
  • Serine Proteinase Inhibitors / pharmacology
  • Triticum / metabolism*
  • Trypsin Inhibitors / analysis


  • Plant Proteins
  • Recombinant Proteins
  • Serine Proteinase Inhibitors
  • Trypsin Inhibitors
  • WSCI protein, Triticum
  • Chymotrypsin
  • Pancreatic Elastase
  • Leukocyte Elastase