Affiliation:
1. Laboratoire de Génétique Moléculaire des Champignons, UMR-5095 CNRS et Université de Bordeaux 2, IBGC, 1 rue Camille Saint-Saëns, 33077 Bordeaux Cedex, France
Abstract
ABSTRACT
Vegetative incompatibility is a programmed cell death reaction that occurs when fungal cells of unlike genotypes fuse. Genes defining vegetative incompatibility (
het
genes) are highly polymorphic, and most if not all incompatibility systems include a protein partner bearing the fungus-specific domain termed the HET domain. The nonallelic
het-C
/
het-E
incompatibility system is the best-characterized incompatibility system in
Podospora anserina
. Cell death is triggered by interaction of specific alleles of
het-C
, encoding a glycolipid transfer protein, and
het-E
, encoding a HET domain and a WD repeat domain involved in recognition. We show here that overexpression of the isolated HET domain from
het-E
results in cell death. This cell death is characterized by induction of autophagy, increased vacuolization, septation, and production of lipid droplets, which are hallmarks of cell death by incompatibility. In addition, the HET domain lethality is suppressed by the same mutations as vegetative incompatibility, but not by the inactivation of
het-C
. These results establish the HET domain as the mediator of cell death by incompatibility and lead to a modular conception of incompatibility systems whereby recognition is ensured by the variable regions of incompatibility proteins and cell death is triggered by the HET domain.
Publisher
American Society for Microbiology
Subject
Molecular Biology,General Medicine,Microbiology
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