scispace - formally typeset
Search or ask a question
Journal ArticleDOI

Anchoring and length regulation of Porphyromonas gingivalis Mfa1 fimbriae by the downstream gene product Mfa2.

TL;DR: Co-immunoprecipitation demonstrated that Mfa2 and Mfa1 are associated with each other in whole P. gingivalis cells, and immunogold microscopy confirmed that MFA2 was located on the cell surface and likely associated with Mfa 1 fimbriae.
Abstract: Porphyromonas gingivalis, a causative agent of periodontitis, has at least two types of thin, single-stranded fimbriae, termed FimA and Mfa1 (according to the names of major subunits), which can be discriminated by filament length and by the size of their major fimbrilin subunits. FimA fimbriae are long filaments that are easily detached from cells, whereas Mfa1 fimbriae are short filaments that are tightly bound to cells. However, a P. gingivalis ATCC 33277-derived mutant deficient in mfa2, a gene downstream of mfa1, produced long filaments (10 times longer than those of the parent), easily detached from the cell surface, similar to FimA fimbriae. Longer Mfa1 fimbriae contributed to stronger autoaggregation of bacterial cells. Complementation of the mutant with the wild-type mfa2 allele in trans restored the parental phenotype. Mfa2 is present in the outer membrane of P. gingivalis, but does not co-purify with the Mfa1 fimbriae. However, co-immunoprecipitation demonstrated that Mfa2 and Mfa1 are associated with each other in whole P. gingivalis cells. Furthermore, immunogold microscopy, including double labelling, confirmed that Mfa2 was located on the cell surface and likely associated with Mfa1 fimbriae. Mfa2 may therefore play a role as an anchor for the Mfa1 fimbriae and also as a regulator of Mfa1 filament length. Two additional downstream genes (pgn0289 and pgn0290) are co-transcribed with mfa1 (pgn0287) and mfa2 (pgn0288), and proteins derived from pgn0289, pgn0290 and pgn0291 appear to be accessory fimbrial components.
Citations
More filters
Journal ArticleDOI
TL;DR: Underpinning many of these processes are intracellular phosphorylation events that regulate a large number of microbial interactions relevant to community formation and development, which co-localize species in mutually beneficial relationships.
Abstract: Establishment of a community is considered to be essential for microbial growth and survival in the human oral cavity. Biofilm communities have increased resilience to physical forces, antimicrobial agents and nutritional variations. Specific cell-to-cell adherence processes, mediated by adhesin-receptor pairings on respective microbial surfaces, are able to direct community development. These interactions co-localize species in mutually beneficial relationships, such as streptococci, veillonellae, Porphyromonas gingivalis and Candida albicans. In transition from the planktonic mode of growth to a biofilm community, microorganisms undergo major transcriptional and proteomic changes. These occur in response to sensing of diffusible signals, such as autoinducer molecules, and to contact with host tissues or other microbial cells. Underpinning many of these processes are intracellular phosphorylation events that regulate a large number of microbial interactions relevant to community formation and development.

158 citations

Book ChapterDOI
TL;DR: The virulence factors of periodontal pathogens, especially P. gingivalis, are discussed, and their roles in regulating immune responses during periodontitis progression are discussed.
Abstract: Periodontitis is an infection-driven inflammatory disease, which is characterized by gingival inflammation and bone loss. Periodontitis is associated with various systemic diseases, including cardiovascular, respiratory, musculoskeletal, and reproductive system related abnormalities. Recent theory attributes the pathogenesis of periodontitis to oral microbial dysbiosis, in which Porphyromonas gingivalis acts as a critical agent by disrupting host immune homeostasis. Lipopolysaccharide, proteases, fimbriae, and some other virulence factors are among the strategies exploited by P. gingivalis to promote the bacterial colonization and facilitate the outgrowth of the surrounding microbial community. Virulence factors promote the coaggregation of P. gingivalis with other bacteria and the formation of dental biofilm. These virulence factors also modulate a variety of host immune components and subvert the immune response to evade bacterial clearance or induce an inflammatory environment. In this chapter, our focus is to discuss the virulence factors of periodontal pathogens, especially P. gingivalis, and their roles in regulating immune responses during periodontitis progression.

120 citations

Journal ArticleDOI
21 Apr 2016-Cell
TL;DR: The Bacteroidia pilus, therefore, has a biogenesis mechanism that is distinct from other known pili and likely represents a different type of bacterial pilus.

69 citations


Cites background or result from "Anchoring and length regulation of ..."

  • ...…main structural pilins (FimA [major] or Mfa1 [minor]) that form the stalk of the pilus (Park et al., 2005; Sojar et al., 1991), followed by genes for the anchors pilins (FimB [major] and Mfa2 [minor]) and other ancillary pilins or regulatory elements (Hasegawa et al., 2009; Nagano et al., 2010)....

    [...]

  • ...Consistent with previous results (Hasegawa et al., 2009), three to four times longer Mfa1 pili were produced by mutants without Mfa2, compared to WT (Figures 5D and 5E)....

    [...]

  • ...Previous studies showed that anchor pilins (Mfa2 and FimB) of both minor and major pili from P. gingivalis are located at the pili base and regulate their length (Hasegawa et al., 2009; Nagano et al., 2010)....

    [...]

Journal ArticleDOI
TL;DR: A possible nonsense mutation within fimB, immediately downstream from fimA, coding a major subunit of FimA fimbriae of the strains of Porphyromonas gingivalis is found, suggesting that FimB functions as an anchor of the fimbRIae.
Abstract: The periodontitis-associated pathogen Porphyromonas gingivalis colonizes and forms a biofilm in gingival crevices through fimbriae. It is known that the often-used strains ATCC 33277 and 381 produce long FimA fimbriae. We found a possible nonsense mutation within fimB, immediately downstream from fimA, coding a major subunit of FimA fimbriae of the strains. Indeed, P. gingivalis strains, except for ATCC 33277 and 381, universally expressed FimB, the gene product of fimB. Electron micrographs revealed that a FimB-restored strain had short and dense, "toothbrush"-like, FimA fimbriae. FimA overexpression elongated the fimbriae, whereas FimB overexpression shortened them. FimB restoration increased production of FimA and its accessory proteins. Thus, FimB regulates the length and expression of FimA fimbriae. Additionally, FimB restoration significantly reduced the release of FimA fimbriae from the cell surface, suggesting that FimB functions as an anchor of the fimbriae. The restoration enhanced adherent activity as well.

38 citations


Cites background from "Anchoring and length regulation of ..."

  • ...Our group recently reported that Mfa2 of P. gingivalis also played a role in length regulation and cell anchoring of Mfa1 fimbriae (Hasegawa et al., 2009)....

    [...]

  • ...gingivalis also played a role in length regulation and cell anchoring of Mfa1 fimbriae (Hasegawa et al., 2009)....

    [...]

  • ...However, PapH/Mfa2 were copurified with each type of fimbria (Verger et al., 2006; Hasegawa et al., 2009), but we do not have experimental evidence thus far that FimB is associated with FimA fimbriae....

    [...]

Journal ArticleDOI
05 Oct 2015-PLOS ONE
TL;DR: The results indicate that the accessory proteins Mfa3, Mfa4, and Mfa5 are necessary for assembly of Mfa1 fimbriae and regulation of auto-aggregation and biofilm formation of P. gingivalis.
Abstract: Porphyromonas gingivalis, a gram-negative obligate anaerobic bacterium, is considered to be a key pathogen in periodontal disease. The bacterium expresses Mfa1 fimbriae, which are composed of polymers of Mfa1. The minor accessory components Mfa3, Mfa4, and Mfa5 are incorporated into these fimbriae. In this study, we characterized Mfa4 using genetically modified strains. Deficiency in the mfa4 gene decreased, but did not eliminate, expression of Mfa1 fimbriae. However, Mfa3 and Mfa5 were not incorporated because of defects in posttranslational processing and leakage into the culture supernatant, respectively. Furthermore, the mfa4-deficient mutant had an increased tendency to auto-aggregate and form biofilms, reminiscent of a mutant completely lacking Mfa1. Notably, complementation of mfa4 restored expression of structurally intact and functional Mfa1 fimbriae. Taken together, these results indicate that the accessory proteins Mfa3, Mfa4, and Mfa5 are necessary for assembly of Mfa1 fimbriae and regulation of auto-aggregation and biofilm formation of P. gingivalis. In addition, we found that Mfa3 and Mfa4 are processed to maturity by the same RgpA/B protease that processes Mfa1 subunits prior to polymerization.

33 citations

References
More filters
Journal ArticleDOI
TL;DR: This manuscript is a brief primer on microbial ecology, because, although the importance of microbial ecology in periodontal diseases is widely recognized, most of us do not know precisely what the term means.
Abstract: The authors have taken the liberty of presenting this manuscript in two parts. The first is a brief primer on microbial ecology, because, although the importance of microbial ecology in periodontal diseases is widely recognized, most of us do not know precisely what is meant by the term. The second section is a rather extensive overview of current studies of oral microbial ecology based almost entirely on recent in vivo studies.

1,490 citations


"Anchoring and length regulation of ..." refers background in this paper

  • ...Porphyromonas gingivalis is a Gram-negative, black-pigmented, obligate anaerobe that has been implicated in adult periodontitis (Lamont & Jenkinson, 1998; Socransky & Haffajee, 2005), which is a major cause of tooth loss in the adult population....

    [...]

Journal ArticleDOI
TL;DR: Curli provide a unique system to study macromolecular assembly in bacteria and in vivo amyloid fiber formation and their role in pathogenesis is reviewed.
Abstract: Curli are the major proteinaceous component of a complex extracellular matrix produced by many Enterobacteriaceae. Curli were first discovered in the late 1980s on Escherichia coli strains that caused bovine mastitis, and have since been implicated in many physiological and pathogenic processes of E. coli and Salmonella spp. Curli fibers are involved in adhesion to surfaces, cell aggregation, and biofilm formation. Curli also mediate host cell adhesion and invasion, and they are potent inducers of the host inflammatory response. The structure and biogenesis of curli are unique among bacterial fibers that have been described to date. Structurally and biochemically, curli belong to a growing class of fibers known as amyloids. Amyloid fiber formation is responsible for several human diseases including Alzheimer's, Huntington's, and prion diseases, although the process of in vivo amyloid formation is not well understood. Curli provide a unique system to study macromolecular assembly in bacteria and in vivo amyloid fiber formation. Here, we review curli biogenesis, regulation, role in biofilm formation, and role in pathogenesis.

1,055 citations


"Anchoring and length regulation of ..." refers background in this paper

  • ...Fimbriae, pili or curli are adhesive hair-like organelles that project from the cell surface of a wide variety of Gramnegative as well as Gram-positive bacteria (Barnhart & Chapman, 2006; Capitani et al., 2006; Pizarro-Cerda & Cossart, 2006)....

    [...]

Journal ArticleDOI
TL;DR: Although periodontal disease is localized to the tissues surrounding the tooth, evidence is accumulating that infection with P. gingivalis may predispose to more serious systemic conditions such as cardiovascular disease and to delivery of preterm infants.
Abstract: Porphyromonas gingivalis, a gram-negative anaerobe, is a major etiological agent in the initiation and progression of severe forms of periodontal disease. An opportunistic pathogen, P. gingivalis can also exist in commensal harmony with the host, with disease episodes ensuing from a shift in the ecological balance within the complex periodontal microenvironment. Colonization of the subgingival region is facilitated by the ability to adhere to available substrates such as adsorbed salivary molecules, matrix proteins, epithelial cells, and bacteria that are already established as a biofilm on tooth and epithelial surfaces. Binding to all of these substrates may be mediated by various regions of P. gingivalis fimbrillin, the structural subunit of the major fimbriae. P. gingivalis is an asaccharolytic organism, with a requirement for hemin (as a source of iron) and peptides for growth. At least three hemagglutinins and five proteinases are produced to satisfy these requirements. The hemagglutinin and proteinase genes contain extensive regions of highly conserved sequences, with posttranslational processing of proteinase gene products contributing to the formation of multimeric surface protein-adhesin complexes. Many of the virulence properties of P. gingivalis appear to be consequent to its adaptations to obtain hemin and peptides. Thus, hemagglutinins participate in adherence interactions with host cells, while proteinases contribute to inactivation of the effector molecules of the immune response and to tissue destruction. In addition to direct assault on the periodontal tissues, P. gingivalis can modulate eucaryotic cell signal transduction pathways, directing its uptake by gingival epithelial cells. Within this privileged site, P. gingivalis can replicate and impinge upon components of the innate host defense. Although a variety of surface molecules stimulate production of cytokines and other participants in the immune response, P. gingivalis may also undertake a stealth role whereby pivotal immune mediators are selectively inactivated. In keeping with its strict metabolic requirements, regulation of gene expression in P. gingivalis can be controlled at the transcriptional level. Finally, although periodontal disease is localized to the tissues surrounding the tooth, evidence is accumulating that infection with P. gingivalis may predispose to more serious systemic conditions such as cardiovascular disease and to delivery of preterm infants.

983 citations


"Anchoring and length regulation of ..." refers background in this paper

  • ...Porphyromonas gingivalis is a Gram-negative, black-pigmented, obligate anaerobe that has been implicated in adult periodontitis (Lamont & Jenkinson, 1998; Socransky & Haffajee, 2005), which is a major cause of tooth loss in the adult population....

    [...]

  • ...Fimbriae also play a major role in adhesion to and invasion of gingival epithelial cells by P. gingivalis (Andrian et al., 2006; Lamont & Jenkinson, 1998)....

    [...]

Journal ArticleDOI
TL;DR: Considering that the majority of oral bacteria are organized in dense three-dimensional biofilms on teeth, confocal microscopy and fluorescently labeled probes provide valuable approaches for investigating the architecture of these organized communities in situ.
Abstract: Human oral bacteria interact with their environment by attaching to surfaces and establishing mixed-species communities. As each bacterial cell attaches, it forms a new surface to which other cells can adhere. Adherence and community development are spatiotemporal; such order requires communication. The discovery of soluble signals, such as autoinducer-2, that may be exchanged within multispecies communities to convey information between organisms has emerged as a new research direction. Direct-contact signals, such as adhesins and receptors, that elicit changes in gene expression after cell-cell contact and biofilm growth are also an active research area. Considering that the majority of oral bacteria are organized in dense three-dimensional biofilms on teeth, confocal microscopy and fluorescently labeled probes provide valuable approaches for investigating the architecture of these organized communities in situ. Oral biofilms are readily accessible to microbiologists and are excellent model systems for studies of microbial communication. One attractive model system is a saliva-coated flowcell with oral bacterial biofilms growing on saliva as the sole nutrient source; an intergeneric mutualism is discussed. Several oral bacterial species are amenable to genetic manipulation for molecular characterization of communication both among bacteria and between bacteria and the host. A successful search for genes critical for mixed-species community organization will be accomplished only when it is conducted with mixed-species communities.

908 citations


"Anchoring and length regulation of ..." refers background in this paper

  • ...gingivalis, and contribute to the formation of mixed-species biofilms on oral surfaces (Jenkinson & Lamont, 2005; Kolenbrander et al., 2002; Yoshimura et al., 2009)....

    [...]

  • ...Fimbriae are one of the major colonization factors of P. gingivalis, and contribute to the formation of mixed-species biofilms on oral surfaces (Jenkinson & Lamont, 2005; Kolenbrander et al., 2002; Yoshimura et al., 2009)....

    [...]

Journal ArticleDOI
24 Feb 2006-Cell
TL;DR: Bacteria use monomeric adhesins/invasins or highly sophisticated macromolecular machines to establish a complex host/pathogen molecular crosstalk that leads to subversion of cellular functions and establishment of disease.

840 citations


"Anchoring and length regulation of ..." refers background in this paper

  • ...Fimbriae, pili or curli are adhesive hair-like organelles that project from the cell surface of a wide variety of Gramnegative as well as Gram-positive bacteria (Barnhart & Chapman, 2006; Capitani et al., 2006; Pizarro-Cerda & Cossart, 2006)....

    [...]