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Formation of methyl mercaptan from L-methionine by Porphyromonas gingivalis
M Yoshimura1, Y Nakano, Y Yamashita
1Department of Preventive Dentistry, Kyushu University Faculty of Dental Science, Fukuoka 812-8582, Japan.
Abstract:
Methyl mercaptan production by oral bacteria is thought to be one of the main causes of oral malodor. We examined the ability of periodontopathic Porphyromonas gingivalis to produce methyl mercaptan from L-methionine and found that the invasive strains W83 and W50 produced large amounts of methyl mercaptan. We cloned and sequenced the mgl gene encoding L-methionine-alpha-deamino-gamma-mercaptomethane-lyase (METase) from P. gingivalis W83. The structural mgl gene consisted of 1,200 bp and encoded a 43.3-kDa protein. To examine the role of methyl mercaptan in the pathogenesis of P. gingivalis, a METase-deficient mutant of P. gingivalis W83 was constructed. The methionine degradation activity and virulence of the mutant (M1217) and the parent strain (W83) in mice were compared. M1217 showed a marked decrease in the formation of methyl mercaptan from L-methionine and decreased virulence compared with the wild-type strain W83. These results suggest that methyl mercaptan not only is one of the sources of oral malodor, but may also play a role in the pathogenicity of P. gingivalis.
Insights
Oral bacteria like Porphyromonas gingivalis produce methyl mercaptan, a cause of bad breath. This study shows methyl mercaptan also contributes to P. gingivalis pathogenicity, impacting virulence.
Area of Science:
- Microbiology
- Oral Health
- Biochemistry
Background:
- Methyl mercaptan (CH3SH) production by oral bacteria is a primary cause of oral malodor.
- Periodontopathic bacteria, such as Porphyromonas gingivalis, are implicated in severe oral conditions.
Purpose of the Study:
- To investigate the role of Porphyromonas gingivalis in methyl mercaptan production from L-methionine.
- To determine the contribution of methyl mercaptan to the pathogenicity of P. gingivalis.
Main Methods:
- Cloning and sequencing of the mgl gene encoding L-methionine-alpha-deamino-gamma-mercaptomethane-lyase (METase) in P. gingivalis W83.
- Construction of a METase-deficient mutant (M1217) of P. gingivalis W83.
- Comparison of methionine degradation activity and virulence in mice between the mutant and wild-type strains.
Main Results:
- P. gingivalis strains W83 and W50 produced significant amounts of methyl mercaptan from L-methionine.
- The mgl gene consists of 1,200 bp, encoding a 43.3-kDa METase protein.
- The METase-deficient mutant M1217 exhibited reduced methyl mercaptan production and decreased virulence compared to the wild-type W83.
Conclusions:
- Methyl mercaptan production by P. gingivalis contributes to oral malodor.
- Methyl mercaptan plays a role in the pathogenicity of P. gingivalis, influencing its virulence.