Downy Mildew effector HaRxL21 interacts with the transcriptional repressor TOPLESS to promote pathogen susceptibility

• DOI: 10.1371/journal.ppat.1008835
• Publication Date: 2020-08-12T18:34:20Z
• Authors: Sarah Harvey; Priyanka Kumari; Dmitry Lapin; Thomas Griebel; Richard Hickman; Wenbin Guo; Runxuan Zhang; Jane E. Parker; Jim Beynon; Katherine Denby; Jens Steinbrenner
• Keywords: 0301 basic medicine; /dk/atira/pure/subjectarea/asjc/1300/1311; /dk/atira/pure/subjectarea/asjc/1300/1312; name=Virology; /dk/atira/pure/subjectarea/asjc/2400/2404; QH301-705.5; Virulence Factors; /dk/atira/pure/subjectarea/asjc/2400/2405; name=Genetics; /dk/atira/pure/subjectarea/asjc/2400/2406; Immunology; Arabidopsis; arabidopsis-thaliana; Microbiology; 03 medical and health sciences; name=Parasitology; Gene Expression Regulation, Plant; 500 Naturwissenschaften und Mathematik::580 Pflanzen (Botanik)::580 Pflanzen (Botanik); Virology; Genetics; Plant Immunity; name=Immunology; /dk/atira/pure/subjectarea/asjc/2400/2403; Biology (General); gene; Molecular Biology; innate immunity; Plant Diseases; 580; 0303 health sciences; triggered immunity; Virulence; Arabidopsis Proteins; ear motif; 500; name=Molecular Biology; RC581-607; receptor-like kinase; cell-surface; Oomycetes; name=Microbiology; Host-Pathogen Interactions; Parasitology; Immunologic diseases. Allergy; protein; Research Article

AbstractHyaloperonospora arabidopsidis (Hpa) is an oomycete pathogen causing Arabidopsis downy mildew. Effector proteins secreted from the pathogen into the plant play key roles in promoting infection by suppressing plant immunity and manipulating the host to the pathogen’s advantage. One class of oomycete effectors share a conserved ‘RxLR’ motif critical for their translocation into the host cell. Here we characterize the interaction between an RxLR effector, HaRxL21 (RxL21), and the Arabidopsis transcriptional co-repressor Topless (TPL). We establish that RxL21 and TPL interact via an EAR motif at the C-terminus of the effector, mimicking the host plant mechanism for recruiting TPL to sites of transcriptional repression. We show that this motif, and hence interaction with TPL, is necessary for the virulence function of the effector. Furthermore, we provide evidence that RxL21 uses the interaction with TPL, and its close relative TPL-related 1, to repress plant immunity and enhance host susceptibility to both biotrophic and necrotrophic pathogens.