RT Journal Article
SR Electronic
T1 Multiple variants of the blast fungus effector AVR-Pik bind the HMA domain of the rice protein OsHIPP19 with high affinity
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2020.12.01.403451
DO 10.1101/2020.12.01.403451
A1 Josephine H. R. Maidment
A1 Marina Franceschetti
A1 Abbas Maqbool
A1 Hiromasa Saitoh
A1 Chatchawan Jantasuriyarat
A1 Sophien Kamoun
A1 Ryohei Terauchi
A1 Mark J. Banfield
YR 2020
UL http://biorxiv.org/content/early/2020/12/01/2020.12.01.403451.abstract
AB Microbial plant pathogens secrete effector proteins which manipulate the host to promote infection. Effectors can be recognised by plant intracellular nucleotide-binding leucine-rich repeat (NLR) receptors, initiating an immune response. The AVR-Pik effector from the rice blast fungus Magnaporthe oryzae is recognised by a pair of rice NLR receptors, Pik-1 and Pik-2. Pik-1 contains a non-canonical integrated heavy metal-associated (HMA) domain, which directly binds AVR-Pik to activate plant defences. Non-canonical integrated domains are widespread in plant NLRs and are thought to resemble the host target of the recognised effector. AVR-Pik interacts with specific rice HMA domain-containing proteins, namely heavy metal-associated isoprenylated plant proteins (HIPPs) and heavy metal-associated plant proteins (HPPs). Here, we define the biochemical and structural basis of the interaction between AVR-Pik and OsHIPP19, and compare the interaction with the HMA domain of Pik-1. Using analytical gel filtration and surface plasmon resonance, we show that multiple AVR-Pik variants, including the stealthy variants AVR-PikC and AVR-PikF which do not interact with any characterised Pik-1 alleles, bind to OsHIPP19 with nanomolar affinity. The crystal structure of OsHIPP19 in complex with AVR-PikF reveals differences at the interface that underpin high-affinity binding of OsHIPP19-HMA to a wider set of AVR-Pik variants than achieved by the integrated HMA domain of Pik-1. Our results provide a foundation for engineering the HMA domain of Pik-1 to extend binding to currently unrecognised AVR-Pik variants and expand disease resistance in rice to divergent pathogen strains.Competing Interest StatementThe authors have declared no competing interest.