DIACYLGLYCEROL KINASE IS INVOLVED IN REGULATION OF EXPRESSION OF THE LANTIBIOTIC MUTACIN-II OF STREPTOCOCCUS-MUTANS

Genetic characterization of a Tn916 transposon mutant, Streptococcus m utans T8-1 defective in mutacin II production, revealed that the trans poson was inserted into the 3' region of a diacylglycerol kinase (dgk) gene. The insertion occurred in the same region as described for anot her S. mutans mutant, GS5Tn1, which was altered in its ability to resp ond to environmental stress (Y. Yamashita, T. Takehara, and H. K. Kura mitsu, J. Bacteriol, 175:6220-6228, 1993). Quantitative primer extensi on from the mutacin structural gene mutA showed a decreased level (abo ut eightfold) of mutA transcription for mutant T8-1. Mutacin productio n was restored by transforming mutant T8-1 with integration vector pVA 891 containing an intact dgk gene, These data indicated that the full- length dgk gene product along with the mutacin biosynthetic operon are required for the production of the mutacin II lantibiotic.