Biology subjects

Dwibedi, C.

Publications and source records attributed to Dwibedi, C..

2 recordsLinked to original sources

bioRxiv2025

Characterization and description of Clostridium filamentum ETTB, a novel gut bacterium with TLR5 modulating properties

The Clostridium genus is highly heterogeneous, encompassing numerous species and strains, many of which remain to be isolated and characterized to better understand their relationship to host physiology. This study aimed to isolate and characterize novel bacterial species within the Clostridium genus and explore their potential links to host health. Under microaerophilic conditions, we isolated and characterized three bacterial isolates belonging to a new anaerobic Clostridium species, designating Clostridium sp. DSM 115107 (Clostridium filamentum ETTB3) as the type strain. C. filamentum ETTB isolates are rod- to filament-shaped, Gram-positive bacteria and exhibit poor growth when cultured on rich media such as LYBHI. Genome sequencing and phylogenetic analysis revealed that C. filamentum ETTB belongs to the Clostridium genus and clusters closely with Clostridium saudiense JCC. Interestingly, C. filamentum ETTB has a significantly smaller genome compared to C. saudiense JCC containing a reduced repertoire of genes involved in carbohydrate degradation and amino acid synthesis and a larger number of genes related to cell motility, including an additional copy of the fliC gene. Unlike C. saudiense, C. filamentum ETTB adopted a filamentous morphology when in contact with Caco-2 cells and stimulate the TLR5 pathway in Caco-2 cells. Metagenomics analysis revealed that C. filamentum ETTB is present in both industrialized and non-industrialized populations, although the relative abundance varying considerably between and within individuals. Our study identifies a novel bacterial strain adapted for the human gut that has the potential to influence host immune response by activating TLR5 pathway.

microbiology↗

bioRxiv2024

BPP43_05035 is a Brachyspira pilosicoli cell surface adhesin that weakens the integrity of the epithelial barrier during infection

The anaerobic spirochete Brachyspira causes intestinal spirochetosis, characterized by the intimate attachment of bacterial cells to the colonic mucosa, potentially leading to symptoms such as diarrhea, abdominal pain, and weight loss. Despite the clinical significance of Brachyspira infections, the mechanism behind the interaction between Brachyspira and the colonic epithelium is not known. In this study, we characterized the molecular mechanism of B. pilosicoli-epithelium interaction and its impact on the epithelial barrier during infection. Through a proteomics approach, we identified BPP43_05035 as a candidate B. pilosicoli adhesion protein that mediates bacterial attachment to cultured human colonic epithelial cells. The crystal structure of BPP43_05035 revealed a globular lipoprotein with a six-bladed beta-propeller domain. Blocking the native BPP43_05035 on B. pilosicoli, either with a specific antibody or via competitive inhibition, abrogated its binding to epithelial cells. Furthermore, the binding of BPP43_05035 to epithelial cells required surface-exposed host N-glycans. Proximity labeling and interaction assays revealed that BPP43_05035 bound to tight junctions, thereby increasing the permeability of the epithelial monolayer. Extending our investigation to human patients, we identified a downregulation of tight junction and brush border genes in B. pilosicoli-infected patients carrying detectible levels of epithelium-bound BPP43_05035. Collectively, our findings identify BPP43_05035 as a B. pilosicoli adhesin that weakens the colonic epithelial barrier during infection.

microbiology↗