The Porphyromonas gingivalis hemagglutinins HagB and HagC are major mediators of adhesion and biofilm formation

Abstract

Porphyromonas gingivalis is a bacterium associated with chronic periodontitis that possesses a family of genes encoding hemagglutinins required for heme acquisition. In this study we generated ΔhagB and ΔhagC mutants in strain W83 and demonstrate that both hagB and hagC are required for adherence to oral epithelial cells. Unexpectedly, a double ΔhagB/ΔhagC mutant had less severe adherence defects than either of the single mutants, but was found to exhibit increased expression of the gingipain-encoding genes rgpA and kgp, suggesting that a ΔhagB/ΔhagC mutant is only viable in populations of cells that exhibit increased expression of genes involved in heme acquisition. Disruption of hagB in the fimbriated strain ATCC33277 demonstrated that HagB is also required for stable attachment of fimbriated bacteria to oral epithelial cells. Mutants of hagC were also found to form defective single and multi-species biofilms that had reduced biomass relative to biofilms formed by the wild-type strain. This study highlights the hitherto unappreciated importance of these genes in oral colonization and biofilm formation.

Isolates fromMonechma ciliatumseeds' extract hamperedPorphyromonas gingivalishemagglutinins

“…like gingipains, and potential adhesion molecules such as hemagglutinins, all of which are known as virulence factors (Connolly et al, 2017). The most important virulence factor that P. gingivalis produces is the hemagglutinins (Han, Whitlock, & Progulske-Fox, 1996;Lee, Hillman, & Progulske-Fox, 1996;Shi et al, 1999).…”

Synthesis of ppGpp impacts type IX secretion and biofilm matrix formation in Porphyromonas gingivalis

“…This result is consistent with a previous study by Connolly et al, which showed that P. gingivalis W83 exhibited typical black colonies, whereas ΔhagBΔ-hagC mutant produced white colonies. 3 In addition, our results showed that the parent strain increased the level of ppGpp in response to hemin starvation (Fig. 1b).…”

“…1a, while no phenotype was observed in the single mutants, the double mutant (ΔrelΔrshB) exhibited less heme-binding capacity (black pigmentation), especially in broth culture. Since heme plays an essential role in the growth, protection against oxidative stress, and virulence of P. gingivalis, 3,36 we hypothesized that hemin deprivation could be a key stressor that triggers accumulation of (p)ppGpp in P. gingivalis.…”

“…Porphyromonas gingivalis is an anaerobic bacterium belonging to the phylum Bacteroidetes that persists within the oral microbiome, and is strongly associated with the progression of chronic periodontitis. 1,2 This bacterium is metabolically unusual, it obtains its iron from heme, 3,4 and it does not metabolize sugars; instead, it is highly proteolytic, obtaining its carbon, nitrogen, and energy from protein substrates. [5][6][7][8] For this reason, secretion of proteolytic enzymes into its environment is central to P. gingivalis physiology.…”

Identification of Hemagglutinin Protein from Streptococcus pneumoniae Pili as a Vaccine Candidate by Proteomic Analysis

“…[23] In another experiment conducted by Conolly et al [24] Porphyromonas ginggivalis has hemagglutinin protein pili which acts in adhesion on the epitel cell of mouth, colonization, and biofilm formation.…”