Recognition of the Magnaporthe oryzae effector AVR-Pia by the decoy domain of the rice NLR immune receptor RGA5

BGPI : équipe 4Nucleotide-binding domain and leucine-rich repeat proteins (NLRs) are important receptors in plant immunity that allow recognition of pathogen effectors. The rice NLR RGA5 recognizes the Magnaporthe oryzae effector AVR-Pia through direct interaction. Here, we gained detailed insights into the molecular and structural bases of AVR-Pia-RGA5 interaction and the role of the RATX1 decoy domain of RGA5. NMR titration combined with in vitro and in vivo protein-protein interaction analyses identified the AVR-Pia interaction surface that binds to the RATX1 domain. Structure-informed AVR-Pia mutants showed that, although AVR-Pia associates with additional sites in RGA5, binding to the RATX1 domain is necessary for pathogen recognition, but can be of moderate affinity. Therefore, RGA5-mediated resistance is highly resilient to mutations in the effector. We propose a model that explains such robust effector recognition as a consequence, and an advantage, of the combination of integrated decoy domains with additional independent effector-NLR interactions

The structural landscape and diversity of Pyricularia oryzae MAX effectors revisited

International audienceMagnaporthe AVRs and ToxB-like (MAX) effectors constitute a family of secreted virulence proteins in the fungus Pyricularia oryzae (syn . Magnaporthe oryzae) , which causes blast disease on numerous cereals and grasses. In spite of high sequence divergence, MAX effectors share a common fold characterized by a ß-sandwich core stabilized by a conserved disulfide bond. In this study, we investigated the structural landscape and diversity within the MAX effector repertoire of P . oryzae . Combining experimental protein structure determination and in silico structure modeling we validated the presence of the conserved MAX effector core domain in 77 out of 94 groups of orthologs (OG) identified in a previous population genomic study. Four novel MAX effector structures determined by NMR were in remarkably good agreement with AlphaFold2 (AF2) predictions. Based on the comparison of the AF2-generated 3D models we propose a classification of the MAX effectors superfamily in 20 structural groups that vary in the canonical MAX fold, disulfide bond patterns, and additional secondary structures in N- and C-terminal extensions. About one-third of the MAX family members remain singletons, without strong structural relationship to other MAX effectors. Analysis of the surface properties of the AF2 MAX models also highlights the high variability within the MAX family at the structural level, potentially reflecting the wide diversity of their virulence functions and host targets

Adaptive evolution in virulence effectors of the rice blast fungus Pyricularia oryzae.

Plant pathogens secrete proteins called effectors that target host cellular processes to promote disease. Recently, structural genomics has identified several families of fungal effectors that share a similar three-dimensional structure despite remarkably variable amino-acid sequences and surface properties. To explore the selective forces that underlie the sequence variability of structurally-analogous effectors, we focused on MAX effectors, a structural family of effectors that are major determinants of virulence in the rice blast fungus Pyricularia oryzae. Using structure-informed gene annotation, we identified 58 to 78 MAX effector genes per genome in a set of 120 isolates representing seven host-associated lineages. The expression of MAX effector genes was primarily restricted to the early biotrophic phase of infection and strongly influenced by the host plant. Pangenome analyses of MAX effectors demonstrated extensive presence/absence polymorphism and identified gene loss events possibly involved in host range adaptation. However, gene knock-in experiments did not reveal a strong effect on virulence phenotypes suggesting that other evolutionary mechanisms are the main drivers of MAX effector losses. MAX effectors displayed high levels of standing variation and high rates of non-synonymous substitutions, pointing to widespread positive selection shaping the molecular diversity of MAX effectors. The combination of these analyses with structural data revealed that positive selection acts mostly on residues located in particular structural elements and at specific positions. By providing a comprehensive catalog of amino acid polymorphism, and by identifying the structural determinants of the sequence diversity, our work will inform future studies aimed at elucidating the function and mode of action of MAX effectors

The structural landscape and diversity of Pyricularia oryzae MAX effectors revisited

ABSTRACT Plant pathogenic fungi secrete a wide variety of small proteins, named effectors. Magnaporthe AVRs and ToxB-like (MAX) effectors constitute a superfamily of secreted proteins widely distributed in Pyricularia (syn. Magnaporthe) oryzae , a devastating fungus responsible for blast disease in cereals such as rice. In spite of high evolutionary sequence divergence, MAX effectors share a common fold characterized by a ß-sandwich core often stabilized by a conserved disulfide bond. In this study, we investigated the structural landscape and diversity within this effector family based on a previous phylogenetic analysis of P. oryzae protein sequences that identified 94 ortholog groups (OG) of putative MAX effectors. Combining protein structure modeling approaches and experimental structure determination, we validated the prediction of the conserved MAX core domain for 77 OG clusters. Four novel MAX effector structures determined by NMR were in remarkably good agreement with AlphaFold2 (AF) predictions. Based on the comparison of the AF-generated 3D models we propose an updated classification of the MAX effectors superfamily in 20 structural groups that highlight variation observed in the canonical MAX fold, disulfide bond patterns and decorating secondary structures in N- and C-terminal extensions. About one-third of the MAX family members remain single, showing no obvious structural relationship with other MAX effectors. Analysis of the surface properties of the AF MAX models also highlights the very high variability remaining within the MAX family when examined at the structural level, probably reflecting the wide diversity of their virulence functions and host targets. Author summary MAX effectors are a family of virulence proteins from the plant pathogenic fungus Pyricularia (syn. Magnaporthe) oryzae that share a similar 3D structure despite very low amino-acid sequence identity. Characterizing the function and evolution of these proteins requires a detailed understanding of their structural diversity. We used a combination of experimental structure determination and structural modeling to characterize in detail the MAX effector repertoire of P. oryzae . A prediction pipeline based on similarity searches and structural modeling using the AlphaFold2 (AF) software were used to predict MAX effectors in a collection of 120 P. oryzae genomes. We then compared AF models with experimentally validated NMR structures. The resulting models and experimental structures revealed that the preserved MAX core coexists with extensive structural variability in terms of structured N- or C-terminal extensions. For each of the AF models, we also analyzed the surfaces of the canonical fold that may be involved in protein-protein interactions. This work constitutes a major step in mapping the functional network of MAX effectors through their structure by identifying possible recognition sites that may help focusing studies of their putative targets in infected plant hosts

A comprehensive health effects assessment of the use of sanitizers and disinfectants during COVID-19 pandemic: a global survey

COVID-19 has affected all aspects of human life so far. From the outset of the pandemic, preventing the spread of COVID-19 through the observance of health protocols, especially the use of sanitizers and disinfectants was given more attention. Despite the effectiveness of disinfection chemicals in controlling and preventing COVID-19, there are critical concerns about their adverse effects on human health. This study aims to assess the health effects of sanitizers and disinfectants on a global scale. A total of 91,056 participants from 154 countries participated in this cross-sectional study. Information on the use of sanitizers and disinfectants and health was collected using an electronic questionnaire, which was translated into 26 languages via web-based platforms. The findings of this study suggest that detergents, alcohol-based substances, and chlorinated compounds emerged as the most prevalent chemical agents compared to other sanitizers and disinfectants examined. Most frequently reported health issues include skin effects and respiratory effects. The Chi-square test showed a significant association between chlorinated compounds (sodium hypochlorite and per-chlorine) with all possible health effects under investigation (p-value <0.001). Examination of risk factors based on multivariate logistic regression analysis showed that alcohols and alcohols-based materials were associated with skin effects (OR, 1.98; 95%CI, 1.87-2.09), per-chlorine was associated with eye effects (OR, 1.83; 95%CI, 1.74-1.93), and highly likely with itching and throat irritation (OR, 2.00; 95%CI, 1.90-2.11). Furthermore, formaldehyde was associated with a higher prevalence of neurological effects (OR, 2.17; 95%CI, 1.92-2.44). Furthermore, formaldehyde was associated with a higher prevalence of neurological effects (OR, 2.17; 95%CI, 1.92-2.44). The use of sodium hypochlorite and per-chlorine also had a high chance of having respiratory effects. The findings of the current study suggest that health authorities need to implement more awareness programs about the side effects of using sanitizers and disinfectants during viral epidemics especially when they are used or overused