Identification and functional analysis of glutamine transporter in Streptococcus mutans

Yuko Morikawa, Setsuyo Morimoto, Eri Yoshida, Shuhei Naka, Hiroaki Inaba, Michiyo Matsumoto-Nakano



Background: Streptococcus mutans, a biofilm-forming bacterium, possesses several transporters that function as import/export molecules. Among them, the PII protein family is composed of members that regulate glutamine synthesis in bacterial species. Objective: In this study, we characterized the function of the glutamine transporter in S. mutans MT8148. Methods: The SMU.732 gene, corresponding to glnP in S. mutans, is homologous to the glutamine transporter gene in Bacillus subtilis. We constructed a glnP-inactivated mutant strain (GEMR) and a complement strain (comp-GEMR) and evaluated their biological functions. Results: Growth of GEMR was similar in the presence and absence of glutamine, whereas the growth rates of MT8148 and comp-GEMR were significantly lower in the presence of glutamine as compared to its absence. Furthermore, biofilms formed by MT8148 and comp-GEMR were significantly thicker than that formed by GEMR, while the GEMR strain showed a significantly lower survival rate in an acidic environment than the other strains. Addition of n-phenyl-2-naphthylamine, used to label of the membrane, led to increased fluorescence intensity of MT8148 and GEMR, albeit that was significantly lower in the latter. Conclusions: These results suggest that glnP is associated with glutamine transport in S. mutans, especially the import of glutamine involved in biofilm formation.

ジャーナルJournal of Oral Microbiology
出版ステータスPublished - 1月 1 2020

ASJC Scopus subject areas

  • 歯科学(その他)
  • 微生物学(医療)
  • 感染症


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