Amended Description of the Genes for Synthesis of<i>Actinomyces naeslundii</i>T14V Type 1 Fimbriae and Associated Adhesin

Chen, Ping; Cisar, John O.; Hess, Sonja; Ho, Jenny; Leung, Kai P.

doi:10.1128/iai.01955-06

Cited by 14 publications

(25 citation statements)

References 22 publications

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“…For A. oris, this is achieved by the type 1 fimbriae via their interaction with the salivary PRPs that coat the tooth enamel (14)(15)(16). Although the role of type 1 fimbriae in this interaction was described in the early 1980s (9,16), the molecular architecture, genetics, and machinery for assembly of the covalently linked fimbrial structure, which began to emerge from the pioneering work of Yeung (44), have only recently been elucidated (2,28). Recent advances in this area are due in large part to the development of molecular methods for studies of Gram-positive pili (41) genetic toolbox for Actinomyces (29,43).…”

Section: Discussionmentioning

confidence: 99%

“…By electron microscopy, we showed that FimP forms the fimbrial shaft, with FimQ at the tip (28). Studies by Chen et al (2) showed that a mutant strain lacking the srtC1 sortase failed to produce FimP polymers and exhibited ϳ40% reduction in binding to salivatreated hydroxyapatite (SHA). In contrast, a mutant lacking fimQ displayed ϳ75% reduction in SHA binding, suggesting that FimQ is critical for type 1 fimbria-mediated adhesion reduction.…”

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confidence: 99%

“…While type 1 fimbriae recognize protein receptors, type 2 fimbriae recognize specific saccharide motifs present in both streptococcal coaggregation receptor polysaccharides (RPS) and host cell surface glycoconjugates (5-7). Elucidating the mechanism of assembly of these polymers and the precise molecular nature of the underlying host-bacterial and interbacterial interactions is central to our understanding of the development of oral biofilm and the initiation of inflammation at surrounding sites.The experimental evidence so far (2,28,29,46,47) has established that the assembly of Actinomyces fimbriae occurs by a common sortase-mediated mechanism that was first described in Corynebacterium diphtheriae (41) and later in many other 25,26,32,36,39). In C. diphtheriae, five pilin/fimbrillin-specific sortase genes are organized in three pilus gene clusters (13,38,42).…”

mentioning

confidence: 99%

“…The experimental evidence so far (2,28,29,46,47) has established that the assembly of Actinomyces fimbriae occurs by a common sortase-mediated mechanism that was first described in Corynebacterium diphtheriae (41) and later in many other 25,26,32,36,39). In C. diphtheriae, five pilin/fimbrillin-specific sortase genes are organized in three pilus gene clusters (13,38,42).…”

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confidence: 99%

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Dual Function of a Tip Fimbrillin of Actinomyces in Fimbrial Assembly and Receptor Binding

Mishra

Yang

et al. 2011

J Bacteriol

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Interaction of Actinomyces oris with salivary proline-rich proteins (PRPs), which serve as fimbrial receptors, involves type 1 fimbriae. Encoded by the gene locus fimQ-fimP-srtC1, the type 1 fimbria is comprised of the fimbrial shaft FimP and the tip fimbrillin FimQ. Fimbrial polymerization requires the fimbria-specific sortase SrtC1, which catalyzes covalent linkage of fimbrial subunits. Using genetics, biochemical methods, and electron microscopy, we provide evidence that the tip fimbrillin, FimQ, is involved in fimbrial assembly and interaction with PRPs. Specifically, while deletion of fimP completely abolished the type 1 fimbrial structures, surface display of monomeric FimQ was not affected by this mutation. Surprisingly, deletion of fimQ significantly reduced surface assembly of the type 1 fimbriae. This defect was rescued by recombinant FimQ ectopically expressed from a plasmid. In agreement with the role of type 1 fimbriae in binding to PRPs, aggregation of A. oris with PRP-coated beads was abrogated in cells lacking srtC1 or fimP. This aggregation defect of the ⌬fimP mutant was mainly due to significant reduction of FimQ on the bacterial surface, as the aggregation was not observed in a strain lacking fimQ. Increasing expression of FimQ in the ⌬fimP mutant enhanced aggregation, while overexpression of FimP in the ⌬fimQ mutant did not. Furthermore, recombinant FimQ, not FimP, bound surface-associated PRPs in a dosedependent manner. Thus, not only does FimQ function as the major adhesin of the type 1 fimbriae, it also plays an important role in fimbrial assembly.Dental plaque is a complex biofilm community, the development of which is spatiotemporally regulated by sequential colonization of specific Gram-positive and Gram-negative oral bacteria (18,21,33,34). Attachment of Gram-positive actinomyces and streptococcal species to the tooth surface is a critical early step in biofilm development (33) because their adherence to the tooth surface allows subsequent binding and colonization of both the bridging-type bacteria, such as Fusobacterium nucleatum, and the late colonizers, such as Porphyromonas gingivalis (17,22). The involvement of Actinomyces spp. in this complex process depends on two functionally and antigenically distinct types of cell surface polymeric structures known as fimbriae or pili, which mediate adhesion of actinomyces to dental and mucosal surfaces and interactions with streptococci, as well as other members of the biofilm community (7,33,44). Type 1 fimbriae mediate adhesion of actinomyces to the tooth surface through binding of adsorbed salivary proline-rich proteins (PRPs). This interaction was initially revealed by adhesion of Actinomyces oris T14V to adsorbed acidic PRP1 (16), a nonglycosylated PRP. Subsequent studies (8) showed that other PRPs, including acidic, basic, and glycosylated proteins, also support type 1 fimbria-mediated adhesion. Extensive homology exists between different PRP sequences, which include repeat regions, and the actual sequence or sequences involved in type...

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Dual Function of a Tip Fimbrillin of Actinomyces in Fimbrial Assembly and Receptor Binding

Mishra

Yang

et al. 2011

J Bacteriol

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“…The type I pilus consists of a long rigid structure of repeating subunits that is attached to the cell with a fimbrial tip that recognizes specific substrates. Type I pili have been observed on a number of oral bacteria [50] including P. gingivalis, A. naeslundii [51] and P. intermedia [52]. In Actinomyces oris, type I pili are functional in biofilm formation [53].…”

Section: Extracellular Matrix Compositionmentioning

confidence: 99%

Subgingival Biofilm Structure

Zijnge

Ammann

Thurnheer

et al. 2011

Frontiers of Oral Biology

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Periodontitis is an inflammatory disease of the oral cavity initiated by a microbial biofilm (or 'dental plaque'). Subgingival biofilms in periodontal pockets are not easily analyzed without the loss of structural integrity. These subgingival plaques are structured communities of microorganisms with great phylogenetic diversity embedded in a self-produced extracellular polymeric matrix. For almost three decades, knowledge of the structure of plaque located below the gingival margin has been limited to landmark studies from the 1970s that were unaware of the breadth of microbial diversity we appreciate now. Only recently has technical progress -combining histology, confocal scanning fluorescent microscopy and fluorescent in situ hybridization to localize the most abundant species from different phyla and species associated with periodontitis -provided new insights into the architecture of subgingival biofilms. This review focuses on the structure and composition of subgingival biofilms and discusses current knowledge on the nature of the extracellular matrix. We describe further structural aspects of 'subgingival' biofilms produced in vitro that are gaining considerable interest as we search for models to investigate biofilm development, resistance to antibiotics, extracellular polymeric matrix composition and function, and reciprocal host-cell-to-biofilm interactions. AbstractPeriodontitis is an inflammatory disease of the oral cavity initiated by a microbial biofilm (or 'dental plaque'). Subgingival biofilms in periodontal pockets are not easily analyzed without the loss of structural integrity. These subgingival plaques are structured communities of microorganisms with great phylogenetic diversity embedded in a self-produced extracellular polymeric matrix. For almost three decades, knowledge of the structure of plaque located below the gingival margin has been limited to landmark studies from the 1970s that were unaware of the breadth of microbial diversity we appreciate now. Only recently has technical progress -combining histology, confocal scanning fluorescent microscopy and fluorescent in situ hybridization to localize the most abundant species from different phyla and species associated with periodontitis -provided new insights into the architecture of subgingival biofilms. This review focuses on the structure and composition of subgingival biofilms and discusses current knowledge on the nature of the extracellular matrix. We describe further structural aspects of 'subgingival' biofilms produced in vitro that are gaining considerable interest as we search for models to investigate biofilm development, resistance to antibiotics, extracellular polymeric matrix composition and function, and reciprocal host-cell-to-biofilm interactions.

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Effect of Osteopontin on the Initial Adhesion of Dental Bacteria

2012

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Bacterial biofilms are involved in numerous infections of the human body, including dental caries. While conventional therapy of biofilm diseases aims at eradication and mechanical removal of the biofilms, recent therapeutic approaches target the mechanisms of biofilm formation and bacterial adhesion in particular. The effect of bovine milk osteopontin, a highly phosphorylated whey protein, on adhesion of Streptococcus mitis, Streptococcus sanguinis, and Actinomyces naeslundii, three prominent colonizers in dental biofilms, to saliva-coated surfaces was investigated. While adhesion of A. naeslundii was not affected by osteopontin, a strong, dose-dependent reduction in the number of adhering S. mitis was shown. No difference in bacterial adhesion was observed for caseinoglycomacropeptide, another phosphorylated milk protein. Osteopontin did not affect bacterial viability, but changed bacterial surface hydrophobicity, and may be suggested to prevent the adhesins of S. mitis from interacting with their salivary receptors. The antiadhesive effect of osteopontin may be useful for caries prevention.

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Amended Description of the Genes for Synthesis ofActinomyces naeslundiiT14V Type 1 Fimbriae and Associated Adhesin

Cited by 14 publications

References 22 publications

Dual Function of a Tip Fimbrillin of Actinomyces in Fimbrial Assembly and Receptor Binding

Dual Function of a Tip Fimbrillin of Actinomyces in Fimbrial Assembly and Receptor Binding

Subgingival Biofilm Structure

Effect of Osteopontin on the Initial Adhesion of Dental Bacteria

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