Identification of a Two‐Component Signal Transduction System Involved in Fimbriation of <i>Porphyromonas gingivalis</i>

Hayashi, Jun-ichiro; Nishikawa, Kiyoshi; Hirano, Risa; Noguchi, Toshihide; Yoshimura, Fuminobu

doi:10.1111/j.1348-0421.2000.tb02496.x

Cited by 36 publications

(42 citation statements)

References 20 publications

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“…The in vivo signal that triggers fimbrial expression is not known; however, it has been shown that expression of fimA, which encodes the fimbrillin protein subunit, is affected by environmental and nutritional parameters, since expression was repressed under elevated temperatures or hemin limitation (4,58,88). A two-component system (FimS-FimR) that regulates the expression of fimA was recently discovered (33,81,83), and it has been shown that the response regulator FimR controls expression at the level of transcription (65). Further studies of the function of PG0106 and the regulation of the expression of capsule are required to determine if the expressions of fimbriae and capsule are coordinated.…”

Section: Discussionmentioning

confidence: 99%

Enhanced Biofilm Formation and Loss of Capsule Synthesis: Deletion of a Putative Glycosyltransferase inPorphyromonas gingivalis

Davey¹,

Duncan²

2006

J Bacteriol

112

104

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Periodontitis is a biofilm-mediated disease. Porphyromonas gingivalis is an obligate anaerobe consistently associated with severe manifestations of this disease. As an opportunistic pathogen, the ability to proliferate within and disseminate from subgingival biofilm (plaque) is central to its virulence. Here, we report the isolation of a P. gingivalis transposon insertion mutant altered in biofilm development and the reconstruction and characterization of this mutation in three different wild-type strains. The mutation responsible for the altered biofilm phenotype was in a gene with high sequence similarity (ϳ61%) to a glycosyltransferase gene. The gene is located in a region of the chromosome that includes up to 16 genes predicted to be involved in the synthesis and transport of capsular polysaccharide. The phenotype of the reconstructed mutation in all three wild-type backgrounds is that of enhanced biofilm formation. In addition, in strain W83, a strain that is encapsulated, the glycosyltransferase mutation resulted in a loss of capsule. Further experiments showed that the W83 mutant strain was more hydrophobic and exhibited increased autoaggregation. Our results indicate that we have identified a gene involved in capsularpolysaccharide synthesis in P. gingivalis and that the production of capsule prevented attachment and the initiation of in vitro biofilm formation on polystyrene microtiter plates.The clinical importance of dental plaque and its accessibility for in vivo research makes it one of most studied and bestunderstood biofilm communities. It is now well documented that gram-negative anaerobic bacteria play a significant role in the development of periodontitis, with Porphyromonas gingivalis being implicated as one of the major players in the progression of this chronic disease (10,19,30,61). A number of factors are associated with the virulence of the organism, including a variety of proteases, endotoxins, and collegenases and the production of surface structures, such as fimbriae and capsular polysaccharide (38). This opportunistic pathogen also attaches to and invades human epithelial cells (18,53,56,57), connective tissue, and endothelial cells (15,17,55), and invasion has been shown to be mediated by the expression of fimbriae and a variety of surface adhesins. It is evident that the growth of P. gingivalis within the subgingival plaque is central to the disease process; however, although there have been numerous studies of the pathogenicity of the organism and its interactions with other organisms within the biofilm community, little is known about the molecular-genetic basis of biofilm formation in P. gingivalis.Research on oral biofilms has focused on determining the spatial organization and complex development of plaque by examining the succession of organisms in the growing biofilm. By monitoring the development of the microbial community on the tooth surface after professional cleaning, studies have demonstrated that the early colonizers are primarily grampositive organisms and the late, o...

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Section: Discussionmentioning

confidence: 99%

Enhanced Biofilm Formation and Loss of Capsule Synthesis: Deletion of a Putative Glycosyltransferase inPorphyromonas gingivalis

Davey¹,

Duncan²

2006

J Bacteriol

112

104

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“…In addition, the molecular mechanism involved in the regulation of fimA expression is beginning to be understood. A two-component system (FimS-FimR) that regulates expression has been identified (Hayashi et al, 2000;Watanabe-Kato et al, 1998;Watanabe et al, 1996), and recently it was shown that the response regulator of this two-component system (FimR) controls the expression of these genes at the transcription level (Nishikawa et al, 2004). In regard to mfa1, expression of this gene has been shown to be affected by cell-to-cell contact with a variety of oral streptococci; either upregulation or downregulation was observed, depending on the species (Park et al, 2006).…”

Section: Discussionmentioning

confidence: 99%

A streptococcal effector protein that inhibits Porphyromonas gingivalis biofilm development

Christopher¹,

Arndt

Cugini³

et al. 2010

Microbiology

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Dental plaque formation is a developmental process involving cooperation and competition within a diverse microbial community, approximately 70 % of which is composed of an array of streptococci during the early stages of supragingival plaque formation. In this study, 79 cell-free culture supernatants from a variety of oral streptococci were screened to identify extracellular compounds that inhibit biofilm formation by the oral anaerobe Porphyromonas gingivalis strain 381. The majority of the streptococcal supernatants (61 isolates) resulted in lysis of P. gingivalis cells, and some (17 isolates) had no effect on cell viability, growth or biofilm formation. One strain, however, produced a supernatant that abolished biofilm formation without affecting growth rate. Analysis of this activity led to the discovery that a 48 kDa protein was responsible for the inhibition. Protein sequence identification and enzyme activity assays identified the effector protein as an arginine deiminase. To identify the mechanism(s) by which this protein inhibits biofilm formation, we began by examining the expression levels of genes encoding fimbrial subunits; surface structures known to be involved in biofilm development. Quantitative RT-PCR analysis revealed that exposure of P. gingivalis cells to this protein for 1 h resulted in the downregulation of genes encoding proteins that are the major subunits of two distinct types of thin, single-stranded fimbriae (fimA and mfa1). Furthermore, this downregulation occurred in the absence of arginine deiminase enzymic activity. Hence, our data indicate that P. gingivalis can sense this extracellular protein, produced by an oral streptococcus (Streptococcus intermedius), and respond by downregulating expression of cell-surface appendages required for attachment and biofilm development. INTRODUCTIONHigh cell density and microbial diversity are fundamental to the development and function of the oral biofilm (Kolenbrander et al., 2002). The close proximity of cells within the biofilm facilitates cell-cell interactions, while the diversity offers a wide variety of metabolic functions, allowing the community to acquire nutrients and persist. During plaque formation, organisms affect the activities of one another via physical associations and through the release of extracellular molecules; the effects of these interactions range from mutualistic to antagonistic (Davey & Costerton, 2006;Socransky & Haffajee, 2000). Molecules that are excreted by bacteria into the environment or directly into host cells (through either non-classical or conventional secretion pathways), affecting gene expression of another organism, are often referred to as effectors. The primary objective of this study was to identify effectors produced by oral streptococci that modulate biofilm formation by the oral anaerobe Porphyromonas gingivalis. P. gingivalis is a Gram-negative anaerobe that persists within the oral biofilm community. Outgrowth of this normally commensal organism is associated with severe periodontal disease, r...

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“…This suggested that the sequences upstream of the W50 fimS and the ATCC 33277 fimS are divergent. To confirm this, we designed a forward primer oligonucleotide (fimS_Seq-For) based on the published ATCC 33277 fimS locus sequence (17), repeated the PCR, and sequenced the amplicon. The result confirmed the data of Hayashi et al (17) and showed that the nucleotide sequences upstream of the fimS genes of the two strains are significantly different ( Fig.…”

Section: Genetic and Functional Organization Of Fimr And Fimsmentioning

confidence: 99%

“…It has been assumed that FimR (RR) and FimS (SHK) work in concert as a two-component regulatory system. Inactivation of either fimS or fimR in strain ATCC 33277 resulted in loss of fimbriation (17). Furthermore, FimR has been shown to directly regulate the expression of a limited number of genes, including pg2130, which is associated with FimA fimbriation (37), and mfa1, which encodes the minor fimbrillin Mfa1 (54).…”

mentioning

confidence: 99%

“…The pg1431 gene is predicted to encode a 227-amino-acid, 25.5-kDa putative DNA-binding response regulator of the LuxR family, while the pg1432 gene is located upstream of, and in the same orientation as, pg1431 and is predicted to encode a 621-amino-acid, 70.1-kDa putative sensor histidine kinase. Genes homologous to pg1431 and pg1432 have been identified previously in P. gingivalis strain ATCC 33277 and were designated fimR and fimS, respectively (17); therefore, we designate the W50 pg1431 gene as fimR and the W50 pg1432 gene as fimS. It has been assumed that FimR (RR) and FimS (SHK) work in concert as a two-component regulatory system.…”

mentioning

confidence: 99%

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FimR and FimS: Biofilm Formation and Gene Expression inPorphyromonas gingivalis

Seers

Dashper

et al. 2010

J Bacteriol

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Porphyromonas gingivalis is a late-colonizing bacterium of the subgingival dental plaque biofilm associated with periodontitis. Two P. gingivalis genes, fimR and fimS, are predicted to encode a two-component signal transduction system comprising a response regulator (FimR) and a sensor histidine kinase (FimS). In this study, we show that fimS and fimR, although contiguous on the genome, are not part of an operon. We inactivated fimR and fimS in both the afimbriated strain W50 and the fimbriated strain ATCC 33277 and demonstrated that both mutants formed significantly less biofilm than their respective wild-type strains. Quantitative reverse transcription-real-time PCR showed that expression of fimbriation genes was reduced in both the fimS and fimR mutants of strain ATCC 33277. The mutations had no effect, in either strain, on the P. gingivalis growth rate or on the response to hydrogen peroxide or growth at pH 9, at 41°C, or at low hemin availability. Transcriptome analysis using DNA microarrays revealed that inactivation of fimS resulted in the differential expression of 10% of the P. gingivalis genome (>1.5-fold; P < 0.05). Notably genes encoding seven different transcriptional regulators, including the fimR gene and three extracytoplasmic sigma factor genes, were differentially expressed in the fimS mutant.Two-component signal transduction systems (TCSTS) are used by bacteria to control the expression of a range of genes in response to a variety of environmental and intracellular stimuli. These systems are found in almost all bacteria and are known to regulate an array of physiological traits, including osmoregulation (4), virulence (8), and quorum sensing (21). The crucial role of TCSTS in governing the signaling and regulatory pathways associated with biofilm development has been well documented in many bacteria, including Escherichia coli, Pseudomonas aeruginosa, and Streptococcus mutans (11,25,39). Typically, each TCSTS functions via a phosphorylation cascade and consists of a membrane-bound or cytoplasmic sensor histidine kinase (SHK), which perceives a particular stimulus, and a cytoplasmic response regulator (RR), which allows the cell to respond to the stimulus accordingly via regulation of gene expression (49).Porphyromonas gingivalis is a Gram-negative anaerobe that has been strongly implicated as a major etiologic agent in the onset and progression of chronic periodontitis (47, 55), a disease of the supporting tissues of the teeth. P. gingivalis is a late colonizer of subgingival dental plaque, a complex and dynamic polymicrobial biofilm (22, 31), and its ability to persist as part of a subgingival plaque biofilm is dependent on its adherence to and colonization of the subgingival niche. P. gingivalis has been shown to adhere to primary plaque-colonizing species, particularly Streptococcus spp. such as Streptococcus gordonii (24,29,33,48). Binding of P. gingivalis to S. gordonii has been shown to result in the formation of a bispecies biofilm with P. gingivalis attached to S. gordonii bound to a s...

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Identification of a Two‐Component Signal Transduction System Involved in Fimbriation of Porphyromonas gingivalis

Cited by 36 publications

References 20 publications

Enhanced Biofilm Formation and Loss of Capsule Synthesis: Deletion of a Putative Glycosyltransferase inPorphyromonas gingivalis

Enhanced Biofilm Formation and Loss of Capsule Synthesis: Deletion of a Putative Glycosyltransferase inPorphyromonas gingivalis

A streptococcal effector protein that inhibits Porphyromonas gingivalis biofilm development

FimR and FimS: Biofilm Formation and Gene Expression inPorphyromonas gingivalis

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