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Poster

Session: Session 1 Presenting Authors at Posters (Odds)

P-439 - Purifying and resolving the barley MLA13-AVRA13 heterodimer and other protein complexes from Nicotiana benthamiana for analysis by cryo-EM

Monday, July 14, 2025
13:30 - 15:15  
Location: Confex Hall 3
Structure Informed Synthetic Biology: From Design to Function

    Presenting Author(s)

  • AL

    Aaron Lawson

    Postdoctoral researcher
    Max Planck Institute for Plant Breeding Research
    Koln, Nordrhein-Westfalen, Germany

    • Author(s)

  • AF

    Andrea Flores-Ibarra

    Postdoctoral researcher
    Institute of Biochemistry, University of Cologne
    Köln, Nordrhein-Westfalen, Germany

  • CA

    Chunpeng An

    Postdoctoral researcher
    Max Planck Institute for Plant Breeding Research
    Köln, Nordrhein-Westfalen, Germany

  • AM

    Arthur Macha

    Postdoctoral researcher
    Institute of Biochemistry, University of Cologne
    Köln, Nordrhein-Westfalen, Germany

  • UN

    Ulla Neumann

    Microscopy specialist
    Max Planck Institute for Plant Breeding Research
    Köln, Nordrhein-Westfalen, Germany

  • MG

    Monika Gunkel

    Institute of Biochemistry, University of Cologne
    Köln, Nordrhein-Westfalen, Germany

  • IS

    Isabel Saur

    Group leader
    University of Cologne, CEPLAS
    Cologne, Nordrhein-Westfalen, Germany

  • JC

    Jijie Chai

    Professor
    Westlake University
    Hangzhou, Zhejiang, China (People's Republic)

  • EB

    Elmar Behrmann

    Professor
    Institute of Biochemistry, University of Cologne
    Köln, Nordrhein-Westfalen, Germany

  • PS

    Paul Schulze-Lefert

    Professor
    Max Planck Institute for Plant Breeding Research
    Köln, Nordrhein-Westfalen, Germany

The interaction between cereals and pathogenic grass powdery mildew fungi is exemplified by sequence variations in an allelic series of barley resistance genes that encode Mildew Locus A (MLA) nucleotide-binding leucine-rich repeat (NLR) immune receptors, which feature an N-terminal coiled-coil domain (CNLs). Each receptor is capable of recognizing a corresponding, strain-specific powdery mildew effector encoded by an avirulence gene (AVRa). In this study, we resolve the cryo-EM structure of barley MLA13 in complex with its matching effector, AVRA13-1. Upon binding to MLA13 in planta, the effector adopts an RNase-like fold. AVRA13-1 interacts with MLA13 primarily through its basal loops, engaging the receptor’s C-terminal leucine-rich repeats (LRRs) as well as the central winged helix domain (WHD). By integrating structural insights from the MLA13–AVRA13-1 complex with sequence alignments of other MLA receptors, we introduced a single amino acid mutation in MLA7 that enhances its ability to recognize both AVRA13-1 and its virulent variant AVRA13-V2. These findings suggest a conserved structural basis for MLA association with RNase-like effectors and highlight the potential for structure-guided engineering of plant immune receptors to broaden their pathogen effector recognition. In addition, we present how the expression and purification protocol used in this study is versatile and applicable to other protein complexes to be analysed by cryo-EM.