The core genome of the anaerobic oral pathogenic bacterium Porphyromonas gingivalis

Abstract

BackgroundThe Gram negative anaerobic bacterium Porphyromonas gingivalis has long been recognized as a causative agent of periodontitis. Periodontitis is a chronic infectious disease of the tooth supporting tissues eventually leading to tooth-loss. Capsular polysaccharide (CPS) of P. gingivalis has been shown to be an important virulence determinant. Seven capsular serotypes have been described. Here, we used micro-array based comparative genomic hybridization analysis (CGH) to analyze a representative of each of the capsular serotypes and a non-encapsulated strain against the highly virulent and sequenced W83 strain. We defined absent calls using Arabidopsis thaliana negative control probes, with the aim to distinguish between aberrations due to mutations and gene gain/loss.ResultsOur analyses allowed us to call aberrant genes, absent genes and divergent regions in each of the test strains. A conserved core P. gingivalis genome was described, which consists of 80% of the analyzed genes from the sequenced W83 strain. The percentage of aberrant genes between the test strains and control strain W83 was 8.2% to 13.7%. Among the aberrant genes many CPS biosynthesis genes were found. Most other virulence related genes could be found in the conserved core genome. Comparing highly virulent strains with less virulent strains indicates that hmuS, a putative CobN/Mg chelatase involved in heme uptake, may be a more relevant virulence determinant than previously expected. Furthermore, the description of the 39 W83-specific genes could give more insight in why this strain is more virulent than others.ConclusionAnalyses of the genetic content of the P. gingivalis capsular serotypes allowed the description of a P. gingivalis core genome. The high resolution data from three types of analysis of triplicate hybridization experiments may explain the higher divergence between P. gingivalis strains than previously recognized.

Identification of essential genes of the periodontal pathogen Porphyromonas gingivalis

“…was derived from hybridization analysis of 10 different strains to a DNA microarray of annotated genes from strain W83 [38]. Of note, any gene ‘missing’ from strain W83, even if present in all other strains of P. gingivalis , would be considered not part of the ‘core’.…”

“…Comparison of essential genes between bacterial species included in the DEG reveals that a large fraction of essential genes are species-specific. P. gingivalis essential genes cannot simply be inferred from studies in other bacteria, and such studies in P. gingivalis have not been performed to date, although a ‘core’ genome has been described by comparing ten strains by DNA/DNA-hybridization using microarray technology [38]. However, while there is likely to be overlap, a core genome does not equate with the set of genes essential for survival, and likely includes both essential and non-essential genes.…”

Porphyromonas gingivalis infection in gestational diabetes mellitus and survival in tobacco smokers.

“…P. gingivalis capsule polysaccharide (CPS) mutant strain was found to be a more potent inducer of cytokine synthesis by human gingival fibroblasts compared with the corresponding wild-type strain. Thus CPS hampers the innate immune response [102,103]. In an animal model, immunization with P.…”

“…The capsule is another important virulence factor of P. gingivalis [102,103]. Six different serotypes of capsules have been identified depending on capsular polysaccharide Kantigens and their capacity to generate systemic IgG antibodies [104].…”

“…gingivalis ATCC 33277 that are essential in cigarette smoke conditioned GAM using massively parallel sequencing technology [103,311,346,347]. …”