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The fungal ribonuclease-like effector protein CSEP0064/BEC1054 represses plant immunity and interferes with degradation of host ribosomal RNA

DOI: 10.1371/journal.ppat.1007620 DOI Help

Authors: Helen G. Pennington (Imperial College London) , Rhian Jones (Imperial College London; Aix-Marseille Université) , Seomun Kwon (Imperial College London) , Giulia Bonciani (Imperial College London) , Hannah Thieron (RWTH Aachen University) , Thomas Chandler (Imperial College London) , Peggy Luong (Imperial College London) , Sian Natasha Morgan (Imperial College London) , Michal Przydacz (Imperial College London) , Tolga Bozkurt (Imperial College London) , Sarah Bowden (The John Bingham Laboratory, NIAB) , Melanie Craze (The John Bingham Laboratory, NIAB) , Emma J. Wallington (The John Bingham Laboratory, NIAB) , James Garnett (Kings College London) , Mark Kwaaitaal (RWTH Aachen University) , Ralph Panstruga (RWTH Aachen University) , Ernesto Cota (Imperial College London) , Pietro D. Spanu (Imperial College London)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Plos Pathogens , VOL 15

State: Published (Approved)
Published: March 2019
Diamond Proposal Number(s): 17221

Open Access Open Access

Abstract: The biotrophic fungal pathogen Blumeria graminis causes the powdery mildew disease of cereals and grasses. We present the first crystal structure of a B. graminis effector of pathogenicity (CSEP0064/BEC1054), demonstrating it has a ribonuclease (RNase)-like fold. This effector is part of a group of RNase-like proteins (termed RALPHs) which comprise the largest set of secreted effector candidates within the B. graminis genomes. Their exceptional abundance suggests they play crucial functions during pathogenesis. We show that transgenic expression of RALPH CSEP0064/BEC1054 increases susceptibility to infection in both monocotyledonous and dicotyledonous plants. CSEP0064/BEC1054 interacts in planta with the pathogenesis-related protein PR10. The effector protein associates with total RNA and weakly with DNA. Methyl jasmonate (MeJA) levels modulate susceptibility to aniline-induced host RNA fragmentation. In planta expression of CSEP0064/BEC1054 reduces the formation of this RNA fragment. We propose CSEP0064/BEC1054 is a pseudoenzyme that binds to host ribosomes, thereby inhibiting the action of plant ribosome-inactivating proteins (RIPs) that would otherwise lead to host cell death, an unviable interaction and demise of the fungus.

Keywords: Leaves; Ribonucleases; Barley; Ribosomal RNA; Wheat; Genetically modified plants; RNA structure; RNA extraction

Subject Areas: Biology and Bio-materials

Beamlines: I04-Macromolecular Crystallography