Project description:Microbes have evolved elaborate mechanisms to cope with competitors, including the type VIsecretion system (T6SS) of Gram-negative bacteria. The T6SS inhibits target cells through contact-dependent translocation of toxic effector proteins across two cellular membranes via an inverted phage-like apparatus. Proteobacteria accomplish this feat by passage of theT6SS needle through a megadalton-size membrane complex (MC), which is essential for T6SS function. Remarkably, although the phylum Bacteroidota encodes a T6SS, it lacks homologs of the MC. We identified five novel genes, essential for T6SS function, that encode a candidate unique Bacteroidota T6SSMC. We purified the T6SSiii MC and revealed its dimensions using electron microscopy. We identified an intricate protein protein interaction network underlying the assembly of the MC, the stoichiometry of the five TssNQOPR components., tTheir predicted structures were validated using crosslinking mass-spectrometry and we assessed the structural homology with known proteins. Importantly, we determine the connection between the T6SSiii MC and the otherwise conserved baseplate involving the hub protein Tss.Finally, phylogenomic analysis of the distribution of T6SSiii MC genes across the phylum Bacteroidota highlights patterns of conservation including the invariant
Project description:The role of gut microbiome dysbiosis in the pathogenesis of psoriasis has gained increasing attention in recent years. Secukinumab, targeting interleukin (IL)-17, has a promising efficacy in psoriasis treatment. However, it remains unclear the gut microbiota alteration and related functional changes caused by successful secukinumab therapy in psoriatic patients. In our study, we compared fecal microbiome profile between psoriatic patients after secukinumab successful treatment (AT) and the other two groups, psoriatic patients without therapy (BT) and healthy people (H), respectively by using next-generation sequencing targeting 16S ribosomal RNA. Then, shotgun metagenomic sequencing was firstly used to characterize bacterial gut microbial communities and related functional change in AT group. We found that the diversity and structure of the microbial community in AT group were significantly changed compared to that of BT group and H group. AT group showed a microbiota profile characterized by increased proportions of the phylum Firmicute, families Ruminococcaceae, and a reduction in the phylum Bacteroidota (elevated F/B ratio). To detect functional alteration, we discovered that secukinumab treatment may construct a more stable homeostasis of gut microbiome with functional alteration. There were different KEGG pathways such as downregulated cardiovascular diseases pathway and upregulated infectious diseases in AT group. By metagenomic analysis, metabolic functional pathway was changed after secukinumab therapy. It seems that gut microbiota investigation during biologic drug treatment is useful for predicting the efficacy and risks of drug treatment in disease.
Project description:The role of gut microbiome dysbiosis in the pathogenesis of psoriasis has gained increasing attention in recent years. Secukinumab, targeting interleukin (IL)-17, has a promising efficacy in psoriasis treatment. However, it remains unclear the gut microbiota alteration and related functional changes caused by successful secukinumab therapy in psoriatic patients. In our study, we compared fecal microbiome profile between psoriatic patients after secukinumab successful treatment (AT) and the other two groups, psoriatic patients without therapy (BT) and healthy people (H), respectively by using next-generation sequencing targeting 16S ribosomal RNA. Then, shotgun metagenomic sequencing was firstly used to characterize bacterial gut microbial communities and related functional change in AT group. We found that the diversity and structure of the microbial community in AT group were significantly changed compared to that of BT group and H group. AT group showed a microbiota profile characterized by increased proportions of the phylum Firmicute, families Ruminococcaceae, and a reduction in the phylum Bacteroidota (elevated F/B ratio). To detect functional alteration, we discovered that secukinumab treatment may construct a more stable homeostasis of gut microbiome with functional alteration. There were different KEGG pathways such as downregulated cardiovascular diseases pathway and upregulated infectious diseases in AT group. By metagenomic analysis, metabolic functional pathway was changed after secukinumab therapy. It seems that gut microbiota investigation during biologic drug treatment is useful for predicting the efficacy and risks of drug treatment in disease.
Project description:The production of short-chain fatty acids by Firmicutes within the human gastrointestinal tract is recognized as critical for gut health and the progression of a range of disease states. Firmicutes lack many glycan-degrading pathways and instead derive a major proportion of their metabolic precursors from carbohydrates released by glycan-degrading generalists belonging to the Bacteroidota phylum and Bifidobacteriaceae family. Recently, it was shown that Eubacterium rectale, a widespread member of the Firmicutes belonging to the Clostridiales cluster XIVa, can grow on the unusual but ubiquitous plant-derived sugar sulfoquinovose (SQ) using a sulfoglycolytic sulfofructose transaldolase pathway. Here, we show that in addition to SQ, E. rectale can also grow on the SQ glycoside sulfoquinovosyl glycerol (SQGro). The 3D structure of the E. rectale sulfoquinovosidase shares strong structural conservation with SQases from gram-negative bacteria. Using sequence-similarity networks, we provide new biological context to a conserved domain of unknown function protein SftX belonging to DUF4867, which is conserved in the sulfoglycolytic sulfofructose transaldolase pathway and determine its 3D structure. Finally, with the aid of a synthetic mini-human microbiome reconstituted in germ-free mice, we show that an SQ dietary supplement can rescue E. rectale from population crashes that occur upon switching from a high-fibre to a low-fibre, high-fat diet. This suggests that SQ or SQGro has potential as a prebiotic for promoting the maintenance of this important SCFA-producing bacterium within the colonic microbiota.
Project description:Flavobacterium johnsoniae is a free-living member of the Bacteroidota phylum found in soil and water. It is frequently used as a model species for studying a type of gliding motility dependent on the type IX secretion system (T9SS). O-glycosylation has been reported in several Bacteroidota species and the O-glycosylation of S-layer proteins in Tannerella forsythia was shown to be important for certain virulence features. In this study we characterised the O-glycoproteome of F. johnsoniae and identified 325 O-glycosylation sites within 226 glycoproteins. The structure of the major glycan was found to be a hexasaccharide with the sequence Hex–(Me-dHex)–Me-HexA–Pent–HexA–Me-HexNAcA. Bioinformatic localisation of the glycoproteins determined 68 inner membrane proteins, 60 periplasmic proteins, 26 outer membrane proteins, 57 lipoproteins and 9 proteins secreted by the T9SS. The glycosylated sites were predominantly located in the periplasm where they are postulated to be beneficial for protein folding/stability. Six proteins associated with gliding motility or the T9SS were demonstrated to be O-glycosylated.
Project description:The natural compound DMLL alleviates DSS-induced experimental colitis through modulating gut microbiota and metabolic dysbiosis. The phylum of Bacteroidota and genera of norank_f_Muribaculaceae and Ruminococcus with beneficial potential for UC were the major gut flora regulated by DMLL. In terms of microbiota-derived metabolites, DMLL primarily enriched tryptophan metabolites, secondary bile acids and nicotinamide that possess anti-inflammatory activity and proved protection for intestinal epithelial barrier, subsequently altered the metabolic pathways and improved the impaired host gut homeostasis.
Project description:Glioblastoma (GBM) is thought to be driven by a sub-population of cancer stem cells (CSCs) that self-renew and recapitulate tumor heterogeneity, yet remain poorly understood. Here we present a comparative epigenomic analysis of GBM CSCs that reveals widespread activation of genes normally held in check by Polycomb repressors. These activated targets include a large set of developmental transcription factors (TFs) whose coordinated activation is unique to the CSCs. We demonstrate that a critical factor in the set, ASCL1, activates Wnt signaling by repressing the negative regulator DKK1. We show that ASCL1 is essential for maintenance and in vivo tumorigenicity of GBM CSCs. Genomewide binding profiles for ASCL1 and the Wnt effector LEF1 provide mechanistic insight and suggest widespread interactions between the TF module and the signaling pathway. Our findings demonstrate regulatory connections between ASCL1, Wnt signaling and collaborating TFs that are essential for the maintenance and tumorigenicity of GBM CSCs. Histone modification profiling for multiple marks by ChIP-Seq in untreated glioblastoma cancer stem cells, glioblastoma non-stem cells and neural stem cells
Project description:Cell signaling pathways play key roles to coordinate cellular events in development. Notch signaling pathway is highly conserved across all multicellular animals and is known to co- ordinate a multitude of diverse cellular events, including proliferation, differentiation, fate specification, and cell death. Specific functions of the pathway are however highly context- dependent and are not well characterized in post-traumatic regeneration. Here, we use a small-molecule inhibitor of the pathway (DAPT) to demonstrate that Notch signaling is required for proper arm regeneration in the brittle star Ophioderma brevispina, a highly re- generative member of the phylum Echinodermata. We also employ a transcriptome-wide gene expression analysis (RNA-seq) to characterize the downstream genes controlled by the Notch pathway in the brittle star regeneration.