Identification and Characterization of a Novel Adhesin Unique to Oral Fusobacteria

Department of Biological Sciences, School of Dental Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106-4905, USA.
Journal of Bacteriology (Impact Factor: 2.81). 09/2005; 187(15):5330-40. DOI: 10.1128/JB.187.15.5330-5340.2005
Source: PubMed


Fusobacterium nucleatum is a gram-negative anaerobe that is prevalent in periodontal disease and infections of different parts of the body. The organism
has remarkable adherence properties, binding to partners ranging from eukaryotic and prokaryotic cells to extracellular macromolecules.
Understanding its adherence is important for understanding the pathogenesis of F. nucleatum. In this study, a novel adhesin, FadA (Fusobacterium adhesin A), was demonstrated to bind to the surface proteins of the oral mucosal KB cells. FadA is composed of 129 amino acid (aa)
residues, including an 18-aa signal peptide, with calculated molecular masses of 13.6 kDa for the intact form and 12.6 kDa
for the secreted form. It is highly conserved among F. nucleatum, Fusobacterium periodonticum, and Fusobacterium simiae, the three most closely related oral species, but is absent in the nonoral species, including Fusobacterium gonidiaformans, Fusobacterium mortiferum, Fusobacterium naviforme, Fusobacterium russii, and Fusobacterium ulcerans. In addition to FadA, F. nucleatum ATCC 25586 and ATCC 49256 also encode two paralogues, FN1529 and FNV2159, each sharing 31% identity with FadA. A double-crossover
fadA deletion mutant, F. nucleatum 12230-US1, was constructed by utilizing a novel sonoporation procedure. The mutant had a slightly slower growth rate, yet
its binding to KB and Chinese hamster ovarian cells was reduced by 70 to 80% compared to that of the wild type, indicating
that FadA plays an important role in fusobacterial colonization in the host. Furthermore, due to its uniqueness to oral Fusobacterium species, fadA may be used as a marker to detect orally related fusobacteria. F. nucleatum isolated from other parts of the body may originate from the oral cavity.

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Available from: Hameem Kawsar
    • "Generally, Gram-negative bacterial cell attachment to the host eukaryotic cells is mediated by capsule, fimbrial proteins or outer membrane proteins (OMP) (Bavington and Page, 2005). Outer membrane proteins mediating attachment to epithelial cells have been characterized in another species of Fusobacterium; F. nucleatum, a human oral pathogen (Han et al., 2005). We have shown that OMP mediate attachment of F. necrophorum to bovine endothelial cells (Kumar et al., 2013a). "
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    • "For example, in vitro studies showed that S. gordonii provides H 2 O 2 to enhance the expression of ApiA in Aa (Ramsey and Whiteley, 2009). F. nucleatum possesses FadA, which can mediate its interaction with host epithelial cells (Han et al., 2005) and facilitates the penetration of non-invasive bacteria into endothelial cell layers in vitro (Fardini et al., 2011), suggesting that intra-bacterial interactions are potentially important for immunostimulation by non-invasive oral bacteria. "
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