Biology subjects

Petit-Houdenot, Y.

Publications and source records attributed to Petit-Houdenot, Y..

7 recordsLinked to original sources

bioRxiv2024

Zymoseptoria tritici proteins structurally related to UmV-KP4 and UmV-KP6 are toxic to fungi, and define novel structural families of fungal effectors

Fungal effectors play crucial roles in plant infection. Despite low sequence identity, effectors were recently classified into structural families. In this study, we have elucidated the structures of Zt-NIP1 and Mycgr3-91409 effectors of the wheat fungal pathogen Zymoseptoria tritici, using X-ray crystallography and NMR. These effectors displayed a structural homology with, respectively, KP4 and KP6 killer toxins, from UmV dsRNA viruses infecting the corn fungal pathogen Ustilago maydis. Consequently, Zt-NIP1 and Mycgr3-91409 were renamed Zt-KP4-1 and Zt-KP6-1. Orthologs and paralogs of Zt-KP4-1 and Zt-KP6-1 were identified in Zymoseptoria, but not in other fungi, except Ecp2 effectors related to Zt-KP4-1. Assessment of the biological activities of Zt-KP6-1 and Zt-KP4-1 revealed their toxicity to fungi such as Botrytis cinerea and Z. tritici, but not to wheat. A novel pipeline relying on Foldseek and cysteine-pattern constrained HMM searches of AlphaFold2 predicted structures from Uniprot generated a comprehensive inventory of KP4 and KP6 proteins in fungi and plants. A structure-based classification of these proteins revealed four KP4 and three KP6 structural super families. This classification provided far-reaching hypotheses on their biological function and evolution. This unifying structural framework highlights the power of structure determination for the classification of effectors, and their functional investigation.

biochemistry↗

bioRxiv2024

Bioengineering a plant NLR immune receptor with a robust binding interface towards a conserved fungal pathogen effector

Bioengineering of plant immune receptors has emerged as a key strategy for generating novel disease resistance traits to counteract the expanding threat of plant pathogens to global food security. However, current approaches are limited by rapid evolution of plant pathogens in the field and may lack durability when deployed. Here, we show that the rice nucleotide-binding, leucine-rich repeat (NLR) immune receptor Pik-1 can be engineered to respond to a conserved family of effectors from the multihost blast fungus pathogen Magnaporthe oryzae. We switched the effector binding and response profile of the Pik NLR from its cognate rice blast effector AVR-Pik to the host-determining factor Pwl2 by installing a putative host target, OsHIPP43, in place of the native integrated HMA domain (generating Pikm-1OsHIPP43). This chimeric receptor also responded to other PWL alleles from diverse blast isolates. The crystal structure of the Pwl2/OsHIPP43 complex revealed a multifaceted, robust interface that cannot be easily disrupted by mutagenesis, and may therefore provide durable, broad resistance to blast isolates carrying PWL effectors in the field. Our findings highlight how the host targets of pathogen effectors can be used to bioengineer new recognition specificities that have more robust properties compared to naturally evolved disease resistance genes.

plant biology↗

bioRxiv2024

The blast effector Pwl2 is a virulence factor that modifies the cellular localisation of host protein HIPP43 to suppress immunity.

The rice blast fungus Magnaporthe oryzae secretes a battery of effector proteins to facilitate host infection. Among these effectors, Pwl2 was first identified as a host specificity determinant for infection of weeping lovegrass (Eragrostis curvula) and is also recognised by the barley Mla3 resistance gene. However, its biological activity is not known. Here we show that PWL2 expression is regulated by the Pmk1 MAP kinase during cell-to-cell movement by M. oryzae at plasmodesmata (PD)-containing pit field sites. Consistent with its regulation, we provide evidence that Pwl2 binds to a barley heavy metal-binding isoprenylated protein HIPP43, which results in its displacement from plasmodesmata. Transgenic barley lines overexpressing either PWL2 or HIPP43 exhibit attenuated immune responses and increased disease susceptibility. By contrast, a Pwl2SNDEYWY mutant that does not interact with HIPP43, fails to alter the PD localisation of HIPP43. Targeted deletion of three copies of PWL2 in M. oryzae results in a{Delta} pwl2 mutant showing gain-of-virulence to weeping lovegrass and barley Mla3 lines, but also a reduction in severity of blast disease on susceptible host plants. Taken together, our results provide evidence that Pwl2 is a virulence factor that acts by suppressing host immunity through perturbing the plasmodesmatal deployment of HIPP43.

plant biology↗

bioRxiv2022

The neighboring genes AvrLm10A and AvrLm10B are part of a large multigene family of cooperating effector genes conserved in Dothideomycetes and Sordariomycetes

With only a few exceptions, fungal effectors (small secreted proteins) have long been considered as species- or even isolate-specific. With the increasing availability of high-quality fungal genomes and annotations, trans-species or trans-genera families of effectors are being uncovered. Two avirulence effectors, AvrLm10A and AvrLm10B, of Leptosphaeria maculans, the fungus responsible for stem canker of oilseed rape, are members of such a large family of effectors. AvrLm10A and AvrLm10B are neighboring genes, organized in divergent transcriptional orientation. Sequence searches within the L. maculans genome show that AvrLm10A/AvrLm10B belong to a multigene family comprising five pairs of genes with a similar tail-to-tail organization. The two genes in a pair always had the same expression pattern and two expression profiles were distinguished, associated with the biotrophic colonization of cotyledons and / or petioles and stems. Of the two protein pairs further investigated Lmb_jn3_08094/Lmb_jn3_08095 and Lmb_jn3_09745 / Lmb_jn3_09746, one (Lmb_jn3_09745 / Lmb_jn3_09746) had the ability to physically interact, similarly to what was previously described for the AvrLm10A/AvrLm10B pair. AvrLm10A homologues are present in more than 30 Dothideomycete and Sordariomycete plant-pathogenic fungi whereas fewer AvrLm10B homologues were identified. One of the AvrLm10A homologues, SIX5, is an effector from Fusarium oxysporum f.sp. lycopersici physically interacting with the avirulence effector Avr2. We found that AvrLm10A homologues were associated with at least eight distinct putative effector families, suggesting an ability of AvrLm10A/SIX5 to cooperate with diverse effectors. These results point to a general role of the AvrLm10A/SIX5 protein as a cooperator protein, able to interact with diverse families of effectors whose encoding gene is co-regulated with the neighboring AvrLm10A homologue.

plant biology↗

bioRxiv2021

A single amino acid polymorphism in a conserved effector of the multihost blast fungus pathogen expands host-target binding spectrum

Accelerated gene evolution is a hallmark of pathogen adaptation and specialization following host-jumps. However, the molecular processes associated with adaptive evolution between host-specific lineages of a multihost plant pathogen remain poorly understood. In the blast fungus Magnaporthe oryzae (Syn. Pyricularia oryzae), host specialization on different grass hosts is generally associated with dynamic patterns of gain and loss of virulence effector genes that tend to define the distinct genetic lineages of this pathogen. Here, we unravelled the biochemical and structural basis of adaptive evolution of APikL2, an exceptionally conserved paralog of the well-studied rice-lineage specific effector AVR-Pik. Whereas AVR-Pik and other members of the six-gene AVR-Pik family show specific patterns of presence/absence polymorphisms between grassspecific lineages of M. oryzae, APikL2 stands out by being ubiquitously present in all blast fungus lineages from 13 different host species. Using biochemical, biophysical and structural biology methods, we show that a single aspartate to asparagine polymorphism expands the binding spectrum of APikL2 to host proteins of the heavy-metal associated (HMA) domain family. This mutation maps to one of the APikL2-HMA binding interfaces and contributes to an altered hydrogen-bonding network. By combining phylogenetic ancestral reconstruction with an analysis of the structural consequences of allelic diversification, we revealed a common mechanism of effector specialization in the AVR-Pik/APikL2 family that involves two major HMA-binding interfaces. Together, our findings provide a detailed molecular evolution and structural biology framework for diversification and adaptation of a fungal pathogen effector family following host-jumps.

plant biology↗

bioRxiv2020

A new family of structurally conserved fungal effectors displays epistatic interactions with plant resistance proteins

Recognition of a pathogen avirulence (AVR) effector protein by a cognate plant resistance (R) protein triggers a set of immune responses that render the plant resistant. Pathogens can escape this so-called Effector-Triggered Immunity (ETI) by different mechanisms including the deletion or loss-of-function mutation of the AVR gene, the incorporation of point mutations that allow recognition to be evaded while maintaining virulence function, and the acquisition of new effectors that suppress AVR recognition. The Dothideomycete Leptosphaeria maculans, causal agent of oilseed rape stem canker, is one of the few fungal pathogens where suppression of ETI by an AVR effector has been demonstrated. Indeed, AvrLm4-7 suppresses Rlm3- and Rlm9- mediated resistance triggered by AvrLm3 and AvrLm5-9, respectively. The presence of AvrLm4-7 does not impede AvrLm3 and AvrLm5-9 expression, and the three AVR proteins do not appear to physically interact. To decipher the epistatic interaction between these L. maculans AVR effectors, we determined the crystal structure of AvrLm5-9 and obtained a 3D model of AvrLm3, based on the crystal structure of Ecp11-1, a homologous AVR effector candidate from Fulvia fulva. Despite a lack of sequence similarity, AvrLm5-9 and AvrLm3 are structural analogues of AvrLm4-7 (structure previously characterized). Structure-informed sequence database searches identified a larger number of putative structural analogues among L. maculans effector candidates, including the AVR effector AvrLmS-Lep2, all produced during the early stages of oilseed rape infection, as well as among effector candidates from other phytopathogenic fungi. These structural analogues are named LARS (for Leptosphaeria AviRulence and Suppressing) effectors. Remarkably, transformants of L. maculans expressing one of these structural analogues, Ecp11-1, triggered oilseed rape immunity in several genotypes carrying Rlm3. Furthermore, this resistance could be suppressed by AvrLm4-7. These results suggest that Ecp11-1 shares a common activity with AvrLm3 within the host plant which is detected by Rlm3, or that the Ecp11-1 structure is sufficiently close to that of AvrLm3 to be recognized by Rlm3. Author summaryAn efficient strategy to control fungal diseases in the field is genetic control using resistant crop cultivars. Crop resistance mainly relies on gene-for-gene relationships between plant resistance (R) genes and pathogen avirulence (AVR) genes, as defined by Flor in the 1940s. However, such gene-for-gene relationships can increase in complexity over the course of plant-pathogen co-evolution. Resistance against the plant-pathogenic fungus Leptosphaeria maculans by Brassica napus and other Brassica species relies on the recognition of effector (AVR) proteins by R proteins; however, L. maculans produces an effector that suppresses a subset of these specific resistances. Using a protein structure approach, we revealed structural analogy between several of the resistance-triggering effectors, the resistance-suppressing effector, and effectors from other plant-pathogenic species in the Dothideomycetes and Sordariomycetes classes, defining a new family of effectors called LARS. Notably, cross-species expression of one LARS effector from Fulvia fulva, a pathogen of tomato, in L. maculans resulted in recognition by several resistant cultivars of oilseed rape. These results highlight the need to integrate knowledge on effector structures to improve resistance management and to develop broad-spectrum resistances for multi-pathogen control of diseases.

plant biology↗

bioRxiv2019

Fungal effector Jsi1 hijacks plant JA/ET signaling through Topless

Ustilago maydis (U. maydis) is the causal agent of maize smut disease. During the colonization process, the fungus secretes effector proteins which suppress immune responses and redirect the host-metabolism in favor of the pathogen. Here we describe a novel strategy by which U. maydis induces plant jasmonate/ethylene (JA/ET) hormone signaling and thereby biotrophic susceptibility. The U. maydis effector Jasmonate/Ethylene signaling inducer 1 (Jsi1) possesses an ethylene-responsive element binding factor-associated amphiphilic repression (EAR) motif, DLNxxP, which interacts with the second WD40 domain of the conserved plant co-repressor family Topless/Topless related (TPL/TPR). Jsi1 interaction with TPL/TPRs leads to derepression of the ethylene response factor (ERF) branch of the JA/ET signaling pathway, supporting biotrophic susceptibility. Jsi1 likely activates the ERF branch by interfering with the binding of endogenous DLNxxP motif-containing ERF transcription factors to TPL/TPR proteins. The identification of effector proteins possessing a DLNxxP motif in different fungal species with biotrophic and hemibiotrophic lifestyles together with the validation of the interaction between such effectors from Magnaporthe oryzae (M. oryzae), Sporisorium scitamineum (S. scitamineum), and S. reilianum with TPL proteins indicates the convergent evolution of effectors for modulating the TPL/TPR co-repressor hub.

plant biology↗