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[O2-E-AM1-05] Regulation of Reutericyclin production in Streptococcus mutans

〇Hideo Yonezawa¹, Yuichiro Kikuchi¹, Eitoyo Kokubu¹, Kazuyuki Ishihara¹ (1. Dept Microbiol, Tokyo Dent Coll)

Keywords:Streptococcus mutans、ロイテリサイクリン、tetR様regulator

Streptococcus mutans, the principal etiological agent of human dental caries, produces a variety of bacteriocins. One of them, reutericyclin, is the product by a gene cluster consisting of nine ORFs. Within the gene cluster, there are two TetR family transcriptional regulators (MucG and MucH). However, the mechanisms of reutericyclin production by these TetRs has not been clarified. In this study, we investigated the mechanism of gene expression of MucG and MucH. The deletion of mucH showed a loss of antibacterial activity, while deletion of mucG showed an increase in antibacterial activity, as reported previously. In addition, the mucH mutant exhibited a decrease, on the other hand, the mucG mutant showed an increase in the expression of the cluster genes. These results indicated that mucH acts as a positive and mucG as a negative regulator of reutericyclin production. Furthermore, it was suggested that products derived from the gene cluster served as ligands for mucG and mucH to regulate the binding and release to the promoter region. These results indicated that reutericyclin production is uniquely regulated by MucG and MucH.