FimR and FimS: Biofilm Formation and Gene Expression inPorphyromonas gingivalis

Abstract

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...

Melatonin Receptor Agonists as the “Perioceutics” Agents for Periodontal Disease through Modulation of Porphyromonas gingivalis Virulence and Inflammatory Response

“…Amounts of mRNA transcripts were measured by the Roche LightCycler 480 real-time PCR detection system (Roche, Basel, Switzerland). The galE gene was used as the housekeeping amplicon [40]. Reactions were performed with 20 μL of a mixture containing 10 μL of SYBR Premix Ex Taq II (2×; Takara), 1.6 μL of each gene-specific primer, 3.4 μL of sterile distilled water and 5 μL of the cDNA template.…”

“…Reactions were performed with 20 μL of a mixture containing 10 μL of SYBR Premix Ex Taq II (2×; Takara), 1.6 μL of each gene-specific primer, 3.4 μL of sterile distilled water and 5 μL of the cDNA template. The forward and reverse primer sequences are shown in Table 1 [40,41]. Real-time PCR conditions included 30 s at 95°C; 10 s at 95°C, 20 s at 60°C and 15 s at 72°C for 40 cycles.…”

Deletion of Lipoprotein PG0717 in Porphyromonas gingivalis W83 Reduces Gingipain Activity and Alters Trafficking in and Response by Host Cells

“…P. gingivalis has several two-component sensor histidine kinase systems, which have been shown to enhance virulence by regulating the processing or expression of various virulence factors including major fimbriae [10], biofilm production [11], and the maturation and proper localization of gingipains [12]. Therefore, we hypothesized that PG0717 may modulate the virulence of W83 through a similar mechanism, namely, regulation of virulence factor expression or processing.…”

Characterization of Fusobacterium nucleatum ATCC 23726 adhesins involved in strain-specific attachment to Porphyromonas gingivalis

“…43, 44, 45 As our coaggregation experiments are typically performed with planktonically grown cells, we wanted to confirm that the differences seen in coaggregation patterns with the F. nucleatum OMP mutants is relevant for the integration of P. gingivalis strains 4612 and T22 into pre-existing fusobacterial biofilms. P. gingivalis strain 33277 was not included in the biofilm studies because coaggregation reactions with F. nucleatum OMP mutants did not show significant involvement of these adhesins in this interaction.…”