A conserved co-chaperone is required for virulence in fungal plant pathogens.
The maize pathogenic fungus Ustilago maydis experiences endoplasmic reticulum (ER) stress during plant colonization and relies on the unfolded protein response (UPR) to cope with this stress. We identified the U. maydis co-chaperone, designated Dnj1, as part of this conserved cellular response to ER stress. ∆dnj1 cells are sensitive to the ER stressor tunicamycin and display a severe virulence defect in maize infection assays. A dnj1 mutant allele unable to stimulate the ATPase activity of chaperones phenocopies the null allele. A Dnj1-mCherry fusion protein localizes in the ER and interacts with the luminal chaperone Bip1. The Fusarium oxysporum Dnj1 ortholog contributes to the virulence of this fungal pathogen in tomato plants. Unlike the human ortholog, F. oxysporum Dnj1 partially rescues the virulence defect of the Ustilago dnj1 mutant. By enabling the fungus to restore ER homeostasis and maintain a high secretory activity, Dnj1 contributes to the establishment of a compatible interaction with the host. Dnj1 orthologs are present in many filamentous fungi, but are absent in budding and fission yeasts. We postulate a conserved and essential role during virulence for this class of co-chaperones.
Max Planck Institute for Terrestrial Microbiology, Karl-von Frisch-Strasse 10, 35043, Marburg, Germany.
Libera
L
Lo Presti
Departamento de Genética, Campus de Excelencia Internacional Agroalimentario ceiA3, Universidad de Córdoba, 14071, Cordoba, Spain.
Cristina
C
López Díaz
Departamento de Genética, Campus de Excelencia Internacional Agroalimentario ceiA3, Universidad de Córdoba, 14071, Cordoba, Spain.
David
D
Turrà
Departamento de Genética, Campus de Excelencia Internacional Agroalimentario ceiA3, Universidad de Córdoba, 14071, Cordoba, Spain.
Antonio
A
Di Pietro
Department of Molecular Microbiology and Genetics, Georg-August-Universität Göttingen, Grisebachstraße 8, 37077, Göttingen, Germany.
Martin
M
Hampel
Department of Molecular Microbiology and Genetics, Georg-August-Universität Göttingen, Grisebachstraße 8, 37077, Göttingen, Germany.
Kai
K
Heimel
Max Planck Institute for Terrestrial Microbiology, Karl-von Frisch-Strasse 10, 35043, Marburg, Germany.
Regine
R
Kahmann
D017124:Conserved Sequence; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects; D005656:Fungal Proteins / Q000737:chemistry / Q000378:metabolism; D005670:Fusarium / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005816:Genetic Complementation Test; D018832:Molecular Chaperones / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D011485:Protein Binding / Q000187:drug effects; D000072417:Protein Domains; D014415:Tunicamycin / Q000494:pharmacology; D056811:Unfolded Protein Response / Q000187:drug effects; D014588:Ustilago / Q000378:metabolism* / Q000472:pathogenicity*; D014774:Virulence / Q000187:drug effects; D003313:Zea mays / Q000382:microbiology*
D005656:Fungal Proteins; D018832:Molecular Chaperones; D014415:Tunicamycin
Ustilago maydis; co-chaperone; effector secretion; unfolded protein response (UPR); virulence