Involvement of an Skp-Like Protein, PGN_0300, in the Type IX Secretion System of Porphyromonas gingivalis.
The oral Gram-negative anaerobic bacterium Porphyromonas gingivalis is an important pathogen involved in chronic periodontitis. Among its virulence factors, the major extracellular proteinases, Arg-gingipain and Lys-gingipain, are of interest given their abilities to degrade host proteins and process other virulence factors. Gingipains possess C-terminal domains (CTDs) and are translocated to the cell surface or into the extracellular milieu by the type IX secretion system (T9SS). Gingipains contribute to the colonial pigmentation of the bacterium on blood agar. In this study, Omp17, the PGN_0300 gene product, was found in the outer membrane fraction. A mutant lacking Omp17 did not show pigmentation on blood agar and showed reduced proteolytic activity of the gingipains. CTD-containing proteins were released from bacterial cells without cleavage of the CTDs in the omp17 mutant. Although synthesis of the anionic polysaccharide (A-LPS) was not affected in the omp17 mutant, the processing of and A-LPS modification of CTD-containing proteins was defective. PorU, a C-terminal signal peptidase that cleaves the CTDs of other CTD-containing proteins, was not detected in any membrane fraction of the omp17 mutant, suggesting that the defective maturation of CTD-containing proteins by impairment of Omp17 is partly due to loss of function of PorU. In the mouse subcutaneous infection experiment, the omp17 mutant was less virulent than the wild type. These results suggested that Omp17 is involved in P. gingivalis virulence.
Department of Periodontal Science, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan.
Yuko
Y
Taguchi
Division of Microbiology and Oral Infection, Department of Molecular Microbiology and Immunology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
Keiko
K
Sato
Division of Microbiology and Oral Infection, Department of Molecular Microbiology and Immunology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
Hideharu
H
Yukitake
Department of Oral Microbiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan Advanced Research Center for Oral and Craniofacial Sciences, Dental School, Okayama University, Okayama, Japan.
Tetsuyoshi
T
Inoue
Department of Oral Microbiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan Advanced Research Center for Oral and Craniofacial Sciences, Dental School, Okayama University, Okayama, Japan.
Masaaki
M
Nakayama
Division of Microbiology and Oral Infection, Department of Molecular Microbiology and Immunology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
Mariko
M
Naito
Department of Pediatric Dentistry, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
Yoshio
Y
Kondo
Department of Orthodontics, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan.
Konami
K
Kano
Department of Pediatric Dentistry, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
Tomonori
T
Hoshino
Division of Microbiology and Oral Infection, Department of Molecular Microbiology and Immunology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
Koji
K
Nakayama
Department of Periodontal Science, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan.
Shogo
S
Takashiba
Department of Oral Microbiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan Advanced Research Center for Oral and Craniofacial Sciences, Dental School, Okayama University, Okayama, Japan oharan@md.okayama-u.ac.jp.
Naoya
N
Ohara
D018829:Adhesins, Bacterial / Q000276:immunology / Q000378:metabolism*; D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics*; D058947:Bacterial Secretion Systems / Q000276:immunology*; D003546:Cysteine Endopeptidases / Q000276:immunology / Q000378:metabolism*; D000080867:Gingipain Cysteine Endopeptidases; D051379:Mice; D008807:Mice, Inbred BALB C; D010518:Periodontitis / Q000382:microbiology; D016966:Porphyromonas gingivalis / Q000472:pathogenicity*; D021381:Protein Transport; D037521:Virulence Factors / Q000235:genetics*
D018829:Adhesins, Bacterial; D001425:Bacterial Outer Membrane Proteins; D058947:Bacterial Secretion Systems; D000080867:Gingipain Cysteine Endopeptidases; C000607817:Omp17 protein, Porphyromonas gingivalis; D037521:Virulence Factors; D003546:Cysteine Endopeptidases