Analysis of stress response mechanism in oral biofilm formation of S. mutans

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K19265
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 57070:Developmental dentistry-related
• Research Institution: Okayama University
• Principal Investigator: Yasokawa Yuki (松三友紀) 岡山大学, 医歯薬学域, 助教 (90732800)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: Streptococcus mutans / バイオフィルム / プロテオーム

Outline of Final Research Achievements

An important characteristic of Streptococcus mutans, implicated as a primary causative agent of dental caries, is acid tolerance, while the bacterium is also known to survive under acidic conditions, with the molecular chaperone DnaK suggested to be involved in its acid-tolerance mechanism. In this study, S. mutans strains with overexpression (DnaK-o) and suppressed expression (DnaK-s) of the chaperone were constructed and exminations showed strong cell aggregation by the DnaK-o strain under acidic conditions. In addition, the structure of biofilms formed by the DnaK-s strain was sparse as compared to that of those formed by the DnaK-o strain, and those formed by the latter also had significantly greater height. Furthermore, findings regarding DnaK expression indicated the importance of control of cell surface protein expression in regard to biofilm formation. Together, these results suggest that DnaK has an important role related to stress response in biofilm formation by S. mutans.

Free Research Field

小児歯科学分野

Academic Significance and Societal Importance of the Research Achievements

小児歯科臨床において、齲蝕罹患率の低下が認識されているが、齲蝕罹患度は二極化が進んでおり、未だに重症齲蝕を呈する小児も少なくない。主要な齲蝕原性細菌であるS. mutans の菌体表層には多くの病原性の高いタンパクが存在しており、それらの発現により口腔バイオフィルムが形成され病原性を発揮することが知られている。口腔バイオフィルム形成に関与するタンパクを検討することで齲蝕の抑制につながると考えている。