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Arch Biochem Biophys. 2016 Aug 1;603:110-7. doi: 10.1016/j.abb.2016.05.017. Epub 2016 May 28.

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

Author information

1
Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna, Austria.
2
Institute of Molecular Medicine and Cell Research, University of Freiburg, Germany.
3
Department of Chemistry, University of Natural Resources and Life Sciences, Vienna, Austria.
4
The Plant Chemetics Laboratory, Department of Plant Sciences, University of Oxford, United Kingdom.
5
Department of Chemistry and Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Slovenia.
6
Institute of Molecular Medicine and Cell Research, University of Freiburg, Germany; BIOSS Centre for Biological Signaling Studies, University of Freiburg, Germany.
7
Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna, Austria. Electronic address: lukas.mach@boku.ac.at.

Abstract

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

PMID:
27246477
DOI:
10.1016/j.abb.2016.05.017
[Indexed for MEDLINE]
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