9RSV

Complex of rice blast (Magnaporthe oryzae) effector protein AVR-Pia with the HMA domain of OsHPP09 from rice (Oryza sativa)

Summary for 9RSV

• Entry DOI: 10.2210/pdb9rsv/pdb
• Descriptor: Os03g0111400 protein, AVR-Pia protein, SULFATE ION, ... (4 entities in total)
• Functional Keywords: effector, hma, plant protein
• Biological source: Oryza sativa (Asian cultivated rice); More
• Total number of polymer chains: 2
• Total formula weight: 16061.58

Authors

Maidment, J.H.R.,Bocquet, A.,Gelin, M.,De Guillen, K.,Cesari, S. (deposition date: 2025-07-01, release date: 2025-08-27, Last modification date: 2026-08-05)

Primary citation

Maidment, J.H.R.,Saile, S.C.,Bocquet, A.,Thivolle, C.,Bourcet, L.,Planel, L.F.,Gelin, M.,Kroj, T.,Padilla, A.,de Guillen, K.,Cesari, S.
Two folds, many faces: The Magnaporthe oryzae MAX effector AVR-Pia targets novel rice HMA domain-containing proteins.
Plos Pathog., 22:e1014382-e1014382, 2026

PubMed Abstract: Phytopathogenic fungi secrete effector proteins to promote virulence. The MAX (Magnaporthe Avrs and ToxB-like) effectors form a structurally conserved family despite significant sequence diversity. AVR-Pia, a MAX effector from the rice blast fungus Magnaporthe oryzae, is recognised by the model rice nucleotide-binding leucine-rich repeat (NLR) receptor pair OsRGA4/OsRGA5 via direct binding to a heavy metal-associated (HMA) integrated domain (ID) in OsRGA5. While the structural basis of AVR-Pia recognition is well defined, the role of this effector in promoting virulence has remained elusive. Here, we reveal that AVR-Pia specifically interacts with four previously uncharacterised rice HMA domain-containing proteins, three HMA Plant Proteins (OsHPP09, OsHPP10 and OsHPP11), and one HMA Isoprenylated Plant Protein (OsHIPP21). AVR-Pia binds these proteins in vitro and in planta, engaging their HMA domains with differential affinities. Notably, AVR-Pia binds OsHPP09-HMA with considerably higher affinity than the HMA-ID of OsRGA5. By solving the crystal structure of the AVR-Pia/OsHPP09-HMA complex, we identified additional molecular contacts at the interface which underpin high affinity binding. Importantly, the H(I)PPs identified as AVR-Pia interactors are distinct from those bound by the MAX effectors AVR-Pik and Pwl2, underscoring target specialisation within the MAX effector family. Further, structural analyses of the AVR-Pia/OsHPP09-HMA complex revealed a markedly different interface compared to other MAX effector/H(I)PP complexes. Finally, structure-guided mutagenesis of OsHPP09 identified a single residue that is critical for AVR-Pia binding. This work provides structural insight into how distinct MAX effectors exploit HMA domain-containing proteins and offers a foundation towards targeted modification of HMA domains to disrupt effector binding and enhance cereal resistance to blast disease.

PubMed: 42441725
DOI: 10.1371/journal.ppat.1014382

Experimental method

X-RAY DIFFRACTION (1.65 Å)