title: The barley powdery mildew candidate secreted effector protein CSEP0105 inhibits the chaperone activity of a small heat shock protein.
abstract: Pathogens secrete effector proteins to establish a successful interaction with their host. Here, we describe two barley (Hordeum vulgare) powdery mildew candidate secreted effector proteins, CSEP0105 and CSEP0162, which contribute to pathogen success and appear to be required during or after haustorial formation. Silencing of either CSEP using host-induced gene silencing significantly reduced the fungal haustorial formation rate. Interestingly, both CSEPs interact with the barley small heat shock proteins, Hsp16.9 and Hsp17.5, in a yeast two-hybrid assay. Small heat shock proteins are known to stabilize several intracellular proteins, including defense-related signaling components, through their chaperone activity. CSEP0105 and CSEP0162 localized to the cytosol and the nucleus of barley epidermal cells, whereas Hsp16.9 and Hsp17.5 are cytosolic. Intriguingly, only those specific CSEPs changed localization and became restricted to the cytosol when coexpressed with Hsp16.9 and Hsp17.5, confirming the CSEP-small heat shock protein interaction. As predicted, Hsp16.9 showed chaperone activity, as it could prevent the aggregation of Escherichia coli proteins during thermal stress. Remarkably, CSEP0105 compromised this activity. These data suggest that CSEP0105 promotes virulence by interfering with the chaperone activity of a barley small heat shock protein essential for defense and stress responses.
authors.affiliation: Section for Plant and Soil Science, Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, DK-1871 Frederiksberg C, Denmark.
authors.forename: Ali Abdurehim
authors.initials: AA
authors.lastname: Ahmed
authors.affiliation: Section for Plant and Soil Science, Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, DK-1871 Frederiksberg C, Denmark.
authors.forename: Carsten
authors.initials: C
authors.lastname: Pedersen
authors.affiliation: Section for Plant and Soil Science, Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, DK-1871 Frederiksberg C, Denmark.
authors.forename: Torsten
authors.initials: T
authors.lastname: Schultz-Larsen
authors.affiliation: Section for Plant and Soil Science, Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, DK-1871 Frederiksberg C, Denmark.
authors.forename: Mark
authors.initials: M
authors.lastname: Kwaaitaal
authors.affiliation: Section for Plant and Soil Science, Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, DK-1871 Frederiksberg C, Denmark.
authors.forename: Hans Jørgen Lyngs
authors.initials: HJ
authors.lastname: Jørgensen
authors.affiliation: Section for Plant and Soil Science, Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, DK-1871 Frederiksberg C, Denmark htc@plen.ku.dk.
authors.forename: Hans
authors.initials: H
authors.lastname: Thordal-Christensen
mesh_terms: D001203:Ascomycota / Q000472:pathogenicity / Q000502:physiology*; D002467:Cell Nucleus / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000378:metabolism; D005656:Fungal Proteins / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D050888:Heat-Shock Proteins, Small / Q000378:metabolism*; D001467:Hordeum / Q000166:cytology / Q000235:genetics / Q000382:microbiology*; D054884:Host-Pathogen Interactions; D008969:Molecular Sequence Data; D010802:Phylogeny; D010935:Plant Diseases / Q000382:microbiology*; D010940:Plant Proteins / Q000378:metabolism*; D066329:Protein Aggregates; D011485:Protein Binding; D011489:Protein Denaturation; D021381:Protein Transport; D014774:Virulence
chemical_list: D029968:Escherichia coli Proteins; D005656:Fungal Proteins; D050888:Heat-Shock Proteins, Small; D010940:Plant Proteins; D066329:Protein Aggregates