Koji Nakayama

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The gram-negative anaerobic bacterium Porphyromonas gingivalis is a major causative agent of chronic periodontitis. Porphyromonas gingivalis strains have been classified into virulent and less-virulent strains by mouse subcutaneous soft tissue abscess model analysis. Here, we present the whole genome sequence of P. gingivalis ATCC 33277, which is classified(More)
Osteoclasts are multinucleated cells that differentiate from hematopoietic cells and possess characteristics responsible for bone resorption. To study the involvement of mitogen-activated protein kinases (MAPKs) in osteoclastogenesis of the murine monocytic cell line RAW264.7, which can differentiate into osteoclast-like cells in the presence of the(More)
Porphyromonas gingivalis is one of the principal organisms associated with adult periodontitis. Bacterial surface proteins such as fimbriae and gingipain hemagglutinin domains have been implicated as adhesins that actuate colonization of epithelium lining the gingival sulcus. We investigated the genetics of P. gingivalis adhesion to monolayers of epithelial(More)
An Escherichia coli K12 mutant resistant to thymineless death (TLD) was isolated, and its genetic analysis led us to identify a new mutation (recQ1) located between corA and metE on the standard linkage map. The mutation was found to result in increased sensitivity to ultraviolet light and deficiency in conjugational recombination when placed in the recBC(More)
Porphyromonas gingivalis secretes strong proteases called gingipains that are implicated in periodontal pathogenesis. Protein secretion systems common to other Gram-negative bacteria are lacking in P. gingivalis, but several proteins, including PorT, have been linked to gingipain secretion. Comparative genome analysis and genetic experiments revealed 11(More)
Porphyromonas gingivalis is the foremost oral pathogen of adult periodontitis in humans. However, the mechanisms of bacterial invasion and the resultant destruction of the gingival tissue remain largely undefined. We report host-P. gingivalis interactions in primary human gingival fibroblast (HGF) cells. Quantitative immunostaining revealed the need for a(More)
The anaerobic Gram-negative bacterium Porphyromonas gingivalis is a major pathogen in severe forms of periodontal disease and refractory periapical perodontitis. We have recently found that P. gingivalis has a novel secretion system named the Por secretion system (PorSS), which is responsible for secretion of major extracellular proteinases, Arg-gingipains(More)
Inspection of the genomic DNA sequence of the oral anaerobe Porphyromonas gingivalis reveals that the micro-organism possesses the peroxide-sensing transcription activator OxyR, but not the superoxide-sensing transcription factor SoxR. Investigatation of oxidative-stress-responsive proteins in P. gingivalis by two-dimensional gel electrophoresis showed that(More)
The periodontopathogen Porphyromonas gingivalis is an obligate anaerobe that is devoid of catalase but exhibits a relatively high degree of resistance to peroxide stress. In the present study, we demonstrate that P. gingivalis contains a Dps homologue that plays an important role in the protection of cells from peroxide stress. The Dps protein isolated from(More)
The Gram-negative bacterium Porphyromonas gingivalis possesses a number of potential virulence factors for periodontopathogenicity. In particular, cysteine proteinases named gingipains are of interest given their abilities to degrade host proteins and process other virulence factors such as fimbriae. Gingipains are translocated on the cell surface or into(More)