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BpsR modulates Bordetella biofilm formation by negatively regulating the expression of the Bps polysaccharide.

ABSTRACT: Bordetella bacteria are Gram-negative respiratory pathogens of animals, birds, and humans. A hallmark feature of some Bordetella species is their ability to efficiently survive in the respiratory tract even after vaccination. Bordetella bronchiseptica and Bordetella pertussis form biofilms on abiotic surfaces and in the mouse respiratory tract. The Bps exopolysaccharide is one of the critical determinants for biofilm formation and the survival of Bordetella in the murine respiratory tract. In order to gain a better understanding of regulation of biofilm formation, we sought to study the mechanism by which Bps expression is controlled in Bordetella. Expression of bpsABCD (bpsA-D) is elevated in biofilms compared with levels in planktonically grown cells. We found that bpsA-D is expressed independently of BvgAS. Subsequently, we identified an open reading frame (ORF), BB1771 (designated here bpsR), that is located upstream of and in the opposite orientation to the bpsA-D locus. BpsR is homologous to the MarR family of transcriptional regulators. Measurement of bpsA and bpsD transcripts and the Bps polysaccharide levels from the wild-type and the ?bpsR strains suggested that BpsR functions as a repressor. Consistent with enhanced production of Bps, the bpsR mutant displayed considerably more structured biofilms. We mapped the bpsA-D promoter region and showed that purified BpsR protein specifically bound to the bpsA-D promoter. Our results provide mechanistic insights into the regulatory strategy employed by Bordetella for control of the production of the Bps polysaccharide and biofilm formation.

SUBMITTER: Conover MS

PROVIDER: S-EPMC3256665 | biostudies-literature | 2012 Jan

REPOSITORIES: biostudies-literature

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BpsR modulates Bordetella biofilm formation by negatively regulating the expression of the Bps polysaccharide.

Conover Matt S MS Redfern Crystal J CJ Ganguly Tridib T Sukumar Neelima N Sloan Gina G Mishra Meenu M Deora Rajendar R

Journal of bacteriology 20111104 2

Bordetella bacteria are Gram-negative respiratory pathogens of animals, birds, and humans. A hallmark feature of some Bordetella species is their ability to efficiently survive in the respiratory tract even after vaccination. Bordetella bronchiseptica and Bordetella pertussis form biofilms on abiotic surfaces and in the mouse respiratory tract. The Bps exopolysaccharide is one of the critical determinants for biofilm formation and the survival of Bordetella in the murine respiratory tract. In or ...[more]

PMID: 22056934

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Project description:Osteoclastogenesis is essential for bone remodeling and normal skeletal maintenance. Receptor activator of NF-κB ligand (RANKL) promotes osteoclast differentiation and function but requires costimulation of immunoreceptor tyrosine-based activation motif (ITAM)-coupled immunoreceptors. Triggering receptor expressed on myeloid cells-2 (TREM2) coupled to ITAM-adaptor protein DNAX activation protein 12kDA (DAP12) provides costimulation of intracellular calcium signaling during osteoclastogenesis. Previously, we found that downstream of kinase-3 (DOK3) physically associates with DAP12 to inhibit toll-like receptor (TLR)-induced inflammatory signaling in macrophages. However, whether and how DOK3 modulates DAP12-dependent osteoclastogenesis is unknown and the focus of this study. Bone microarchitecture and histology of sex- and age-matched wild-type (WT) and DOK3-deficient (DOK3-/- ) mice were evaluated. Male and female DOK3-/- mice have significantly reduced trabecular bone mass compared with WT mice with increased TRAP+ osteoclasts in vivo. In vitro, DOK3-/- bone marrow-derived macrophages (BMMs) have increased macrophage colony-stimulating factor (M-CSF)-induced proliferation and increased sensitivity to RANKL-induced osteoclastogenesis. Compared with WT, DOK3-/- osteoclasts are significantly larger with more nuclei and have increased resorptive capacity. Mechanistically, DOK3 limits osteoclastogenesis by inhibiting activation of Syk and ERK in response to RANKL and M-CSF. DOK3 is phosphorylated in a DAP12-dependent manner and associates with Grb2 and Cbl. Compared with DAP12-/- mice with high bone mass, DOK3- and DAP12- doubly deficient mice (DKO) have normalized bone mass, indicating that DOK3 also limits DAP12-independent osteoclastogenesis in vivo. In vitro osteoclasts derived from DKO mice are mononuclear with poor resorptive capacity similar to DAP12-/- osteoclasts. Histomorphometry reveals that DOK3-/- mice also have reduced osteoblast parameters. DOK3-/- osteoblasts have reduced in vitro osteoblastogenesis and increased osteoprotegerin (OPG) to RANKL expression ratio compared with WT osteoblasts. Co-culture of WT and DOK3-/- osteoblasts with pre-osteoclasts reveals a reduced capacity of DOK3-/- osteoblasts to support osteoclastogenesis. These data indicate that DOK3 regulates bone remodeling by negatively regulating M-CSF- and RANKL-mediated osteoclastogenesis and positively regulating osteoblastogenesis. © 2017 American Society for Bone and Mineral Research.

Project description:ObjectivesThe present study aimed to evaluate the potential of the salivary pellicle (SP) formed on titanium (Ti) surfaces to modulate the formation of a biofilm composed of Streptococcus gordonii, Actinomyces naeslundii, Fusobacterium nucleatum, and Porphyromonas gingivalis.Materials and methodsTi substrates were incubated for 2 h with a pool of saliva samples obtained from 10 systemically and periodontally healthy subjects. Enamel substrates were included as a biological reference. Scanning electron microscopy (SEM) and Raman spectroscopy analysis were used to analyze the formation of the salivary pellicle. After the SP formation, the surfaces were incubated for 12 h with a mix of Streptococcus gordonii, Actinomyces naeslundii, Fusobacterium nucleatum, and Porphyromonas gingivalis. The number of bacterial cells attached to each surface was determined by the XTT assay while bacterial viability was analyzed by fluorescence microscopy using the LIVE/DEAD® BacLightTM kit.ResultsThe SEM and Raman spectroscopy analysis confirmed the presence of a salivary pellicle formed on the tested surfaces. Regarding the biofilm formation, the presence of the SP decreases the number of the bacterial cells detected in the test surfaces, compared with the uncover substrates. Even more, the SP-covered substrates showed similar bacterial counts in both Ti and enamel surfaces, meaning that the physicochemical differences of the substrates were less determinant than the presence of the SP. While on the SP-uncover substrates, differences in the bacterial adhesion patterns were directly related to the physicochemical nature of the substrates.ConclusionsThe salivary pellicle was the main modulator in the development of the biofilm consisting of representative oral bacteria on the Ti substrates.Clinical relevanceThe results of this study provide valuable information on the modulatory effect of the salivary pellicle on biofilm formation; such information allows us to understand better the events involved in the formation of oral biofilms on Ti dental implants.

Dataset Information

BpsR modulates Bordetella biofilm formation by negatively regulating the expression of the Bps polysaccharide.

Publications

BpsR modulates Bordetella biofilm formation by negatively regulating the expression of the Bps polysaccharide.

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