title: Microarray analysis of the transcriptional responses of Porphyromonas gingivalis to polyphosphate.
abstract: BACKGROUND
  Polyphosphate (polyP) has bactericidal activity against a gram-negative periodontopathogen Porphyromonas gingivalis, a black-pigmented gram-negative anaerobic rod. However, current knowledge about the mode of action of polyP against P. gingivalis is incomplete. To elucidate the mechanisms of antibacterial action of polyP against P. gingivalis, we performed the full-genome gene expression microarrays, and gene ontology (GO) and protein-protein interaction network analysis of differentially expressed genes (DEGs).
  
  
  RESULTS
  We successfully identified 349 up-regulated genes and 357 down-regulated genes (>1.5-fold, P < 0.05) in P. gingivalis W83 treated with polyP75 (sodium polyphosphate, Na(n+2)P(n)O3(n+1); n = 75). Real-time PCR confirmed the up- and down-regulation of some selected genes. GO analysis of the DEGs identified distinct biological themes. Using 202 DEGs belonging to the biological themes, we generated the protein-protein interaction network based on a database of known and predicted protein interactions. The network analysis identified biological meaningful clusters related to hemin acquisition, energy metabolism, cell envelope and cell division, ribosomal proteins, and transposon function.
  
  
  CONCLUSIONS
  polyP probably exerts its antibacterial effect through inhibition of hemin acquisition by the bacterium, resulting in severe perturbation of energy metabolism, cell envelope biosynthesis and cell division, and elevated transposition. Further studies will be needed to elucidate the exact mechanism by which polyP induces up-regulation of the genes related to ribosomal proteins. Our results will shed new light on the study of the antibacterial mechanism of polyP against other related bacteria belonging to the black-pigmented Bacteroides species.
authors.forename: Ji-Hoi
authors.initials: JH
authors.lastname: Moon
authors.forename: Jae-Hyung
authors.initials: JH
authors.lastname: Lee
authors.affiliation: Department of Maxillofacial Biomedical Engineering, School of Dentistry, and Institute of Oral Biology, Kyung Hee University, 26 Kyungheedae-ro, Dongdaemun-gu, Seoul 130-701, Republic of Korea. ljinyong@khu.ac.kr.
authors.forename: Jin-Yong
authors.initials: JY
authors.lastname: Lee
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D020869:Gene Expression Profiling; D046228:Microarray Analysis; D011122:Polyphosphates / Q000494:pharmacology*; D016966:Porphyromonas gingivalis / Q000187:drug effects* / Q000235:genetics*; D060066:Protein Interaction Maps; D013312:Stress, Physiological
chemical_list: D000900:Anti-Bacterial Agents; D011122:Polyphosphates