The death enzyme CP14 is a unique papain-like cysteine proteinase with a pronounced S2 subsite selectivity

Arch Biochem Biophys. 2016 Aug 1;603:110-7. doi: 10.1016/ Epub 2016 May 28.


The cysteine protease CP14 has been identified as a central component of a molecular module regulating programmed cell death in plant embryos. CP14 belongs to a distinct subfamily of papain-like cysteine proteinases of which no representative has been characterized thoroughly to date. However, it has been proposed that CP14 is a cathepsin H-like protease. We have now produced recombinant Nicotiana benthamiana CP14 (NbCP14) lacking the C-terminal granulin domain. As typical for papain-like cysteine proteinases, NbCP14 undergoes rapid autocatalytic activation when incubated at low pH. The mature protease is capable of hydrolysing several synthetic endopeptidase substrates, but cathepsin H-like aminopeptidase activity could not be detected. NbCP14 displays a strong preference for aliphatic over aromatic amino acids in the specificity-determining P2 position. This subsite selectivity was also observed upon digestion of proteome-derived peptide libraries. Notably, the specificity profile of NbCP14 differs from that of aleurain-like protease, the N. benthamiana orthologue of cathepsin H. We conclude that CP14 is a papain-like cysteine proteinase with unusual enzymatic properties which may prove of central importance for the execution of programmed cell death during plant development.

Keywords: Cathepsin; Cell death; Cysteine protease; Degradomics; Plant.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Monoclonal / chemistry
  • Binding Sites
  • Catalysis
  • Cathepsin H / chemistry
  • Cathepsins / chemistry
  • Cysteine Proteases / chemistry*
  • Hydrolysis
  • Insecta
  • Mass Spectrometry
  • Papain / chemistry
  • Peptides / chemistry
  • Plant Proteins / chemistry*
  • Protein Binding
  • Proteomics
  • Recombinant Proteins / chemistry
  • Substrate Specificity
  • Tobacco


  • Antibodies, Monoclonal
  • Peptides
  • Plant Proteins
  • Recombinant Proteins
  • Cathepsins
  • Cysteine Proteases
  • Cathepsin H
  • Papain