Project description:RNA-protein interactions crucially underlie many steps of bacterial gene expression including post-transcriptional control by small regulatory RNAs (sRNAs). In stark contrast with recent progress in Gram-negative bacteria, knowledge about RNA and protein complexes in Gram-positive species remains scarce. Here, we used Grad-seq to draft a landscape of such complexes in Streptococcus pneumoniae, determining the sedimentation profiles of ~88% of the transcripts and ~62% of the proteins of this important human pathogen. Analysis of in-gradient distributions and subsequent tag-based protein capture identified interactions of the exoribonuclease Cbf1 (a.k.a. YhaM) with sRNAs that control bacterial competence. Contrary to expectation, the nucleolytic activity of Cbf1 stabilized these sRNAs, thereby promoting their function as repressors of competence. These results illustrate how this first RNA/protein complexome resource for a Gram-positive species can be utilized to identify new molecular factors in RNA-based regulation of pathways with relevance to bacterial virulence.
Project description:Xenorhabdus nematophila is a Gram-negative bacterium, mutually associated with the soil nematode Steinernema carpocapsae and this nematobacterial complex is parasitic for a broad spectrum of insects. The transcriptional regulator OxyR is widely conserved in bacteria, but the OxyR regulon can vary significantly between species. OxyR activates the transcription of a set of genes that influence cellular defense against oxidative stress. It is also involved in the virulence of several bacterial pathogens. The aim of this study was to identify the X. nematophila OxyR regulon and investigate its role in the bacterial life cycle. An oxyR-mutant was constructed in X. nematophila and phenotypically characterized in vitro and in vivo after reassociation with its nematode partner. OxyR plays a major role during the X. nematophila resistance to oxidative stress in vitro. Transcriptome analysis allowed the identification of 59 genes differentially regulated in the oxyR mutant compared to the parental strain. In vivo, the oxyR mutant was able to reassociate with the nematode as efficiently as the control strain. These nematobacterial complexes harboring the oxyR mutant symbiont were able to rapidly kill the insect larvae in less than 48h after infestation, suggesting that factors other than OxyR could also allow X. nematophila to cope with oxidative stress encountered during this phase of infection in insect. The significant increased number of offspring of the nematobacterial complex when reassociated with the X. nematophila oxyR mutant compared to the control strain, revealed a potential role of OxyR during this symbiotic stage of the bacterial life-cycle.
Project description:Gut microbiota is a constant source of antigens and stimuli to which the resident immune system has developed tolerance. However, the mechanisms by which mononuclear phagocytes, specifically monocytes/macrophages, cope with these usually pro-inflammatory signals is poorly understood. Here, we show that innate immune memory promotes anti-inflammatory homeostasis using as a model strains of the commensal bacterium, Lactiplantibacillus plantarum. Priming of monocytes/macrophages with bacteria, especially in its live form, enhances bacterial intracellular survival and decreases the release of pro-inflammatory signals to the environment, with lower production of TNF and higher levels of IL-10. Analysis of the transcriptomic landscape of these cells shows downregulation of pathways associated with the production of reactive oxygen species (ROS) and the release of cytokines, chemokines and antimicrobial peptides. Indeed, the induction of ROS prevents memory-induced bacterial survival. In addition, there is a dysregulation in gene expression of several metabolic pathways leading to decreased glycolytic and respiratory rates in memory cells. These data support commensal microbe-specific metabolic changes in innate immune memory cells that might contribute to homeostasis in the gut.
Project description:RNA-protein interactions crucially underlie many steps of bacterial gene expression including post-transcriptional control by small regulatory RNAs (sRNAs). In stark contrast with recent progress in Gram-negative bacteria, knowledge about RNA and protein complexes in Gram-positive species remains scarce. Here, we used Grad-seq to draft a landscape of such complexes in Streptococcus pneumoniae, determining the sedimentation profiles of ~88% of the transcripts and ~62% of the proteins of this important human pathogen. Analysis of in-gradient distributions and subsequent tag-based protein capture identified interactions of the exoribonuclease Cbf1 (a.k.a. YhaM) with sRNAs that control bacterial competence. Contrary to expectation, the nucleolytic activity of Cbf1 stabilized these sRNAs, thereby promoting their function as repressors of competence. These results illustrate how this first RNA/protein complexome resource for a Gram-positive species can be utilized to identify new molecular factors in RNA-based regulation of pathways with relevance to bacterial virulence.
Project description:We report here the genome sequence of Filimonas lacunae, a bacterium of the family Chitinophagaceae characterized by high-CO2-dependent growth. The 7.81-Mb circular genome harbors many genes involved in carbohydrate degradation and related genetic regulation, suggesting the role of the bacterium as a carbohydrate degrader in diverse environments.
Project description:This study includes 1146 samples of host genotyping data (genotyped) from Illumina Omni arrays. Samples were collected from adults (>16 yrs) patients with CSF confirmed bacterial meningitis in the Netherlands between 2006 and 2015. Metadata includes patient outcome, species of bacteria, and for 467 samples a link to an ENA run with the associated bacterial genome (S. pneumoniae only).