Project description:Bdelloid rotifers are part of the restricted circle of multicellular animals that can withstand a wide range of genotoxic stresses at any stage of their life cycle. In this study, bdelloid rotifer Adineta vaga was used as a model to decipher the molecular basis of their extreme tolerance. Proteomic analysis showed that a specific DNA ligase, different from those usually involved in DNA repair in eukaryotes, is strongly over-represented upon ionizing radiation. A phylogenetic analysis revealed its orthology to prokaryotic DNA ligase E, and its horizontal acquisition by bdelloid rotifers and plausibly other eukaryotes. The fungus Mortierella verticillata, having a single copy of this DNA Ligase E homolog, also exhibits an increased radiation tolerance with an over-expression of this DNA ligase E following X-ray exposure. We also provide evidence that A. vaga ligase E is a major contributor of DNA breaks ligation activity, which is a common step of all important DNA repair pathways. Consistently, its heterologous expression in human cell lines significantly improved their radio-tolerance. Overall, this study highlights the potential of horizontal gene transfers in eukaryotes, and their contribution to the adaptation to extreme conditions.
Project description:Leaf-to-leaf, systemic immune signaling known as systemic acquired resistance (SAR) is poorly understood in monocotyledonous plants. Here, we characterize systemic immunity in barley (Hordeum vulgare) triggered after primary leaf infection with either Pseudomonas syringae pathovar japonica (Psj) or Xanthomonas translucens pathovar cerealis (Xtc). Both pathogens induced resistance in systemic, uninfected leaves against a subsequent challenge infection with Xtc. In contrast to SAR in Arabidopsis thaliana, systemic immunity in barley was not associated with NONEXPRESSOR OF PATHOGENESIS-RELATED GENES1 or the local or systemic accumulation of salicylic acid (SA). Instead, we documented a moderate local but not systemic induction of abscisic acid (ABA) after infection of leaves with Psj. In contrast to SA or its functional analog benzothiadiazole, local applications of the jasmonic acid methyl ester or ABA triggered systemic immunity to Xtc. RNA-seq analysis of local and systemic transcript accumulation revealed unique gene expression changes in response to both Psj and Xtc and a clear separation of local from systemic responses. The systemic response appeared relatively modest and quantitative RT-PCR associated systemic immunity with the local and systemic induction of two WRKY and two ETHYLENE RESPONSIVE FACTOR-like transcription factors. Systemic immunity against Xtc was further associated with transcriptional changes after a secondary/systemic Xtc challenge infection; these changes were dependent on the primary treatment. Taken together, bacteria-induced systemic immunity in barley may be mediated in part by WRKY and ERF-like transcription factors possibly facilitating transcriptional reprogramming to potentiate immunity.
Project description:Fungal cell walls undergo continual remodeling during hyphal growth, development, infection and adaptation to environmental stress. Cell wall remodeling generates 1,3-glucan fragments by diverse endo-glycosyl hydrolases (GH), which are well-known pathogen-associated molecular patterns (PAMPs). How fungal pathogens evade plant immunity triggered by1,3-glucan fragments and associated GH proteins is not known. Here, we report a novel mechanism of immune evasion underlying the suppression of 1,3-glucan-triggered plant immunity by the blast fungus Magnaporthe oryzae. An exo-1,3-glucanase of the GH17 family, named Ebg1, is important for fungal cell wall integrity and virulence of M. oryzae. Ebg1 can hydrolyze 1,3-glucan and laminarin into glucose to prevent 1,3-glucan-triggered plant immunity, but also acts as a PAMP, independent of its hydrolase activity. Surprisingly, M. oryzae engages an elongation factor 1 alpha protein (EF1 to interact and co-localize with Ebg1 in the apoplast to suppress Ebg1-triggered immunity. Since both Ebg1 and EF1 are widely distributed in fungi, their interaction may be a conserved mechanism whereby fungal pathogens evade plant immunity and safeguard cell wall remodeling during infection.
Project description:Leaf-to-leaf, systemic immune signaling known as systemic acquired resistance (SAR) is poorly understood in monocotyledonous plants. Here, we characterize systemic immunity in barley (Hordeum vulgare) triggered after primary leaf infection with either Pseudomonas syringae pathovar japonica (Psj) or Xanthomonas translucens pathovar cerealis (Xtc). Both pathogens induced resistance in systemic, uninfected leaves against a subsequent challenge infection with Xtc. In contrast to SAR in Arabidopsis thaliana, systemic immunity in barley was not associated with NONEXPRESSOR OF PATHOGENESIS-RELATED GENES1 or the local or systemic accumulation of salicylic acid (SA). Instead, we documented a moderate local but not systemic induction of abscisic acid (ABA) after infection of leaves with Psj. In contrast to SA or its functional analog benzothiadiazole, local applications of the jasmonic acid methyl ester or ABA triggered systemic immunity to Xtc. RNA-seq analysis of local and systemic transcript accumulation revealed unique gene expression changes in response to both Psj and Xtc and a clear separation of local from systemic responses. The systemic response appeared relatively modest and quantitative RT-PCR associated systemic immunity with the local and systemic induction of two WRKY and two ETHYLENE RESPONSIVE FACTOR-like transcription factors. Systemic immunity against Xtc was further associated with transcriptional changes after a secondary/systemic Xtc challenge infection; these changes were dependent on the primary treatment. Taken together, bacteria-induced systemic immunity in barley may be mediated in part by WRKY and ERF-like transcription factors possibly facilitating transcriptional reprogramming to potentiate immunity.
Project description:To understand better the nature of the poor response of human neonates to intracellular pathogens, we evaluated the transcriptome of neonates as compared to adult naïve CD8-T cells. A specific transcription signature of the neonatal cells was found, characterized by a lower expression of signalling and CTL functional genes and a high expression of maturation, cell cycle and innate-immunity associated genes. Functional assays demonstrated that neonatal CD8-T cells undergo homeostatic proliferation, transcribe antimicrobial peptides and produce reactive oxygen species. Master transcription factors were found presumably responsible for this specific signature. Genome wide epigenetic studies showed a corresponding chromatin signature for a number of the differentially expressed genes. Altogether our results show that CD8 neonatal T cells have a particular genetic program with functions within the innate immune response, while still undergoing their maturation process. Neonates are highly susceptible to infections by intracellular pathogens, which are a major cause of infant morbidity and mortality. CD8-T cells control intracellular pathogens through cytotoxic mechanisms in an antigen-dependent manner. We found that human neonatal CD8-T cells, as compared to adult lymphocytes, had a distinctive pattern of gene transcription, characterized by the lower expression of genes involved in TCR signalling and cytotoxicity and a high expression of genes involved in cell cycle and innate immunity. Functional studies corroborated that neonatal CD8-T cells are less cytotoxic, transcribe antimicrobial peptides and produce reactive oxygen species. These properties could explain the high sensitivity of neonates to intracellular pathogen infections and outline novel functions of neonatal CD8-T cells. PBMC total RNAs from Adult and Neonate subjects were profiled after hybridization with Agilent SurePrint G3 Human GE 8x60K Microarray. CD8-T cells mRNA were extracted from 8 samples including: 4 Adults and 4 Neonates.
Project description:Plants have a wide variety of ways to defend against pathogens. A commonly used model of the plant immune system divides it into a general response triggered by pathogen associated molecular patterns (PAMPs) and a specific response triggered by effectors. The first type of response is known as PAMP triggered immunity (PTI) and the second as effector-triggered immunity (ETI). We have performed a proteomical analysis of one PTI and two ETI models in potato and compared their effect on protein expression.
Project description:Diversification of effector function, driven by a co-evolutionary arms race, enables pathogens to establish compatible interactions with their hosts. Structurally conserved plant pathogenesis-related PR-1 and PR-1-like (PR-1L) proteins are involved in plant defense and fungal virulence, respectively. It is unclear how fungal PR-1L counteracts plant defense. Here, we show that Ustilago maydis UmPR-1La and yeast ScPRY1 with conserved phenolic detoxification functions are Ser/Thr-rich region-mediated cell-surface localization proteins. However, UmPR-1La has gained additional specialized activity in eliciting hyphal-like formation, suggesting that U. maydis deploys UmPR-1La to sense phenolics and direct their growth in plants. U. maydis also hijacks plant cathepsin B-like 3 (CatB3) to release functional CAPE-like peptides after cleaving a conserved CNYD motif of UmPR-1La to subvert plant immunity for promoting fungal virulence. Surprisingly, CatB3 avoids cleavage of plant PR-1s, despite the presence of the same conserved CNYD motif. Our work highlights that UmPR-1La has acquired additional dual roles to suppress plant defense and sustain the infection process of fungal pathogens.