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New Phytol. 2018 May;218(3):1156-1166. doi: 10.1111/nph.14446. Epub 2017 Feb 3.

AtSERPIN1 is an inhibitor of the metacaspase AtMC1-mediated cell death and autocatalytic processing in planta.

Author information

1
Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Campus UAB, Bellaterra, Barcelona, 08193, Spain.
2
Department of Plant Systems Biology, VIB, Ghent, 9052, Belgium.
3
Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, 9052, Belgium.
4
LIPM, Université de Toulouse, INRA, CNRS, Castanet-Tolosan, France.
5
Department of Genetics, Universitat de Barcelona and Centre for Research in Agricultural Genomics (CSIC-IRTA-UAB-UB) Edifici CRAG, Campus UAB, Bellaterra, Catalonia, 08193, Spain.
6
Department of Medical Protein Research, VIB, Ghent, 9000, Belgium.
7
Department of Biochemistry, Ghent University, Ghent, 9000, Belgium.
8
Department of Biology, University of North Carolina, Chapel Hill, NC, 27599, USA.
9
Department of Genetics, University of North Carolina, Chapel Hill, NC, 27599, USA.
10
McAllister Heart Institute, University of North Carolina, Chapel Hill, NC, 27599, USA.
11
Lineberger Cancer Center, University of North Carolina, Chapel Hill, NC, 27599, USA.
12
Department of Biology, University of North Carolina, Chapel Hill, NC, 27599-3280, USA.
13
Howard Hughes Medical Institute, University of North Carolina, Chapel Hill, NC, 27599-3280, USA.
14
Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC, 27599-3280, USA.
15
Carolina Center for Genome Sciences, University of North Carolina, Chapel Hill, NC, 27599-3280, USA.
16
Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, NC, 27599-3280, USA.

Abstract

The hypersensitive response (HR) is a localized programmed cell death phenomenon that occurs in response to pathogen recognition at the site of attempted invasion. Despite more than a century of research on HR, little is known about how it is so tightly regulated and how it can be contained spatially to a few cells. AtMC1 is an Arabidopsis thaliana plant metacaspase that positively regulates the HR. Here, we used an unbiased approach to identify new AtMC1 regulators. Immunoaffinity purification of AtMC1-containing complexes led us to the identification of the protease inhibitor AtSerpin1. Our data clearly showed that coimmunoprecipitation between AtMC1 and AtSerpin1 and formation of a complex between them was lost upon mutation of the AtMC1 catalytic site, and that the AtMC1 prodomain was not required for the interaction. AtSerpin1 blocked AtMC1 self-processing and inhibited AtMC1-mediated cell death. Our results constitute an in vivo example of a Serpin acting as a suicide inhibitor in plants, reminiscent of the activity of animal or viral serpins on immune/cell death regulators, including caspase-1. These results indicate a conserved function of a protease inhibitor on cell death regulators from different kingdoms with unrelated modes of action (i.e. caspases vs metacaspases).

KEYWORDS:

hypersensitive response (HR); metacaspase; plant-pathogen interactions; programmed cell death; protease; serpin

PMID:
28157265
DOI:
10.1111/nph.14446
[Indexed for MEDLINE]
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