FIG. 2.

Schematic diagram illustrating the deletions performed on the loci coding for the SMu486/SMu487 TCS in S. mutans UA159. Open reading frames and orientations of transcription are indicated with block arrows. The locations of the DNA sequence fragments that were used for insertion mutagenesis (pIB14) and construction of the complementing plasmid pIB55 are indicated by horizontal lines below SMu486/SMu487. The SMu486, SMu487, and SMu486/SMu487 genes were deleted and replaced with the spectinomycin resistance gene aad (Sp).