GEO accession GSE296366 is currently private and is scheduled to be released on Nov 05, 2025.
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA1259000 | ENA |
REPOSITORIES: ENA
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Project description:Saccharibacteria are episymbionts that require host-bacteria to grow. They are positively associated with inflammatory diseases within the human microbiome, yet their mechanisms for interacting with the human host and contributing to inflammatory diseases remain unknown. This study investigated interactions between a Saccharibacterium (Nanosynbacter lyticus), its host-bacteria (Schaalia odontolytica), and oral epithelial cells. The host-bacteria induced proinflammatory cytokines (IL8, GROα, and MCP-1) in epithelial cells, while Saccharibacteria were immune silent. Remarkably, Saccharibacteria dampened cytokine responses to host-bacteria during coinfection. This effect resulted from Saccharibacteria directly interacting with TLR2 receptors via T4P, becoming endocytosed by epithelial cells, and subsequently inhibiting TLR2 activation by the host-bacteria. Super-resolution imaging showed that intracellular Saccharibacteria colocalized with endosome markers, eventually trafficking to lysosomes. Moreover, a subset survives endocytosis, escapes epithelial cells, and reinfects host-bacteria, highlighting a mechanism for persistence in the oral microbiome and a vital role in mammalian immune system modulation.
2026-02-09 | GSE296366 | GEO
Project description:Type IV pili (T4P) are prevalent, polymeric surface structures in pathogenic bacteria, making them ideal targets for effective vaccines. However, bacteria have evolved efficient strategies to evade type IV pili-directed antibody responses. Neisseria meningitidis are prototypical type IV pili-expressing Gram-negative bacteria responsible for life threatening sepsis and meningitis. This species has evolved several genetic strategies to modify the surface of its type IV pili based on recombination, phase variation and the presence of different alleles of genes involved in posttranslational modifications. This results in changes in pilin subunit amino acid sequence, nature of glycosylation and phosphoform modification, but how these different processes affect antibody binding at the structural level is still unknown. To explore this question, we provide cryo-electron microscopy structures of pili of different sequence types with sufficiently high resolution to visualize posttranslational modifications. We then generated nanobodies directed against type IV pili which alter pilus function in vitro and vivo; and determined their structures complexed with their pilus target. We also determined how the different types of pili surface modifications alter nanobody binding. These different structures shed light on the impressive complementarity between the different strategies used by bacteria to avoid antibody binding. Importantly, we also show that structural information can be used to make informed modifications in nanobodies as countermeasures to these immune evasion mechanisms.
2024-02-29 | PXD046119 | Pride
Project description:The phytopathogen Xylella fastidiosa produces two classes of pili, long type IV pili and short type I pili, which are involved in motility and adhesion. In this work, we have investigated the role of σ54 factor and its involvement in the regulation of fimbrial biogenesis in X. fastidiosa. An rpoN null mutant was constructed from citrus strain J1a12, and analyses of global gene expression profile by microarrays comparing the wild type and rpoN mutant strains showed that few genes exhibited differential expression. At least one gene, pilA1 (XF2542), which encodes the structural pilin protein of type IV fimbriae, showed decreased expression in the rpoN mutant whereas an operon encoding proteins of type I fimbriae were twofold more expressed in the mutant. Quantitative real time RT-PCR (qRT-PCR) analysis confirmed that pilA1 transcript was significantly reduced in the rpoN mutant. The transcriptional start site of pilA1 was determined by primer extension, and a canonical σ54-dependent promoter was found upstream of the start site. Genome sequence analysis of X. fastidiosa revealed five paralogues of pilA, but microarray and qRT-PCR data demonstrated that only the pilA1 transcript was significantly affected in the rpoN mutant. The rpoN mutant made more biofilm than the wild type strain and presented a cell-cell aggregative phenotype. These results indicate that σ54 regulates biofilm formation, probably via differential regulation of genes involved in type IV and type I fimbrial biogenesis. Keywords: rpoN mutant strain, pili
2007-10-22 | GSE8097 | GEO
Project description:Many bacteria express filaments called type IV pili on their surface, which are involved in motility (twitching), surface adhesion, biofilm formation and DNA uptake (natural transformation). Type IV pili are comprised of a helical assembly of repeating pilin subunits that allow both flexibility and strength. They are therefore powerful structures that enable bacterial proliferation and genetic adaptation, potentially leading to the development of pathogenicity and antibiotic resistance. They are also targets for drug development. By electron cryo-microscopy and mass spectrometry, we show that the bacterium Thermus thermophilus produces two forms of type IV pilus, differing in structure and protein composition. We have determined the structures of both and built atomic models, which reveal a new pilin, how the subunits assemble and their glycosylation patterns. We also delineate the roles of the two filaments in promoting twitching and natural transformation.
2020-03-09 | PXD017353 | Pride
Project description:The phytopathogen Xylella fastidiosa produces two classes of pili, long type IV pili and short type I pili, which are involved in motility and adhesion. In this work, we have investigated the role of Ï54 factor and its involvement in the regulation of fimbrial biogenesis in X. fastidiosa. An rpoN null mutant was constructed from citrus strain J1a12, and analyses of global gene expression profile by microarrays comparing the wild type and rpoN mutant strains showed that few genes exhibited differential expression. At least one gene, pilA1 (XF2542), which encodes the structural pilin protein of type IV fimbriae, showed decreased expression in the rpoN mutant whereas an operon encoding proteins of type I fimbriae were twofold more expressed in the mutant. Quantitative real time RT-PCR (qRT-PCR) analysis confirmed that pilA1 transcript was significantly reduced in the rpoN mutant. The transcriptional start site of pilA1 was determined by primer extension, and a canonical Ï54-dependent promoter was found upstream of the start site. Genome sequence analysis of X. fastidiosa revealed five paralogues of pilA, but microarray and qRT-PCR data demonstrated that only the pilA1 transcript was significantly affected in the rpoN mutant. The rpoN mutant made more biofilm than the wild type strain and presented a cell-cell aggregative phenotype. These results indicate that Ï54 regulates biofilm formation, probably via differential regulation of genes involved in type IV and type I fimbrial biogenesis. Direct comparison between wild type strain J1a12 and mutant strain rpoN-.
2010-06-25 | E-GEOD-8097 | biostudies-arrayexpress
Project description:Type IV Pili (T4P) are dynamic surface appendages that mediate adherence, motility, and DNA uptake in Kingella kingae, an important pediatric pathogen that causes osteoarticular infections, bacteremia, and endocarditis. While the major pilin subunit in K. kingae T4P is well characterized, the contribution of minor pilins to T4P structure and function remains unknown. Here, we used proteomics, molecular genetics, biochemical analyses, and structural modeling to identify and characterize all eight minor pilins in K. kingae. We identified a conserved operon of core minor pilin genes encoding FimT, PilV, PilW, PilX, and PilE that promotes surface piliation, adherence to epithelial cells, twitching motility, and natural transformation. Deletion of the fimTpilVWXE locus phenocopied loss of the PilC1 and PilC2 adhesins, and AlphaFold modeling combined with bacterial two-hybrid analysis suggested that FimT, PilV, PilW, and PilX form a complex at the pilus tip. The PilA2, ComP, and KK03_01180 minor pilins were dispensable for adherence and motility but promoted natural transformation and formed protein-protein interactions with the major pilin, suggesting that these proteins are incorporated throughout the pilus shaft. These findings support a new model for the architecture of the K. kingae type IV pilus, with distinct minor pilins localizing to different sites on the pilus fiber and mediating specialized functions essential for virulence.
2025-10-06 | PXD068177 | Pride
Project description:Recent characterization of the obligate episymbiont Saccharibacteria (TM7) belonging to the candidate phyla radiation (CPR) has expanded the extent of microbial diversity. However, the episymbiotic lifestyle of TM7 is still underexploited due to the deficiency of cultivated representatives. Here, we describe gene-targeted TM7 cultivation guided by repurposing epicPCR (emulsion, paired isolation, and concatenation PCR) to capture in situ TM7‒host associations. Using this method, we obtained a novel Saccharibacteria isolate TM7i and its host Leucobacter aridicollis J1 from Cicadae Periostracum, the castoff shell of cicada. Genomic analyses and microscopic characterizations revealed that TM7i could bind to J1 through twitching-like motility mediated by type IV pili (T4P). We further showed that the inhibition of T4P extrusion suppressed the motility and host adherence of TM7i, resulting in its reduced growth. However, the inactivation of T4P had little effect on the growth of TM7i that had already adhered to J1, suggesting the essential role of T4P in host recognition by TM7i. By capturing CPR‒host association and elaborating the T4P-dependent episymbiotic association mechanism, our studies shed light on the distinct yet widespread lifestyle of CPR bacteria.
| S-EPMC9894109 | biostudies-literature
Project description:Pseudomonas aeruginosa lasR QS network promotes phage infection by regulating the biosynthesis of LPS and type IV pili by regulating the biosynthesis of LPS and type IV pili
| PRJNA1034550 | ENA
Project description:All cultivated Patescibacteria, or CPR, exist as obligate episymbionts on other microbes. Despite being ubiquitous in mammals and environmentally, molecular mechanisms of host identification and binding amongst ultrasmall bacterial episymbionts are largely unknown. Type 4 pili (T4P) are well conserved in this group and predicted to facilitate symbiotic interactions. To test this, we targeted T4P pilin genes in Saccharibacteria Nanosynbacter lyticus strain TM7x to assess their essentiality and roles in symbiosis. Our results revealed that N. lyticus assembles two distinct T4P, a non-essential thin pili that has the smallest diameter of any T4P and contributes to host-binding, episymbiont growth, and competitive fitness relative to other Saccharibacteria, and an essential thick pili whose functions include twitching motility. Identification of lectin-like minor pilins and modification of host cell walls suggest glycan binding mechanisms. Collectively our findings demonstrate that Saccharibacteria encode unique extracellular pili that are vital mediators of their underexplored episymbiotic lifestyle.
| S-EPMC11623550 | biostudies-literature
Project description:Candidatus Saccharibacteria bacterium YM_S32_TM7_50_20 Genome sequencing
| PRJNA419966 | ENA