FIG. 1.

Genetic organization of the lactose utilization genes of S. xylosus and nucleotide sequence of the lacR-lacPH promoter region. The lac region that has been sequenced is shown. The size and orientation of the genes were deduced from the nucleotide sequence. The position and orientation of Tn917 in the lacR mutant strain TX258 are marked. The sequence of the lacR-lacP intergenic region is shown. Numbering refers to the complete lac sequence available from the EMBL database under accession no. Y14599. The transcriptional start sites of the lac promoters and an inverted repeat resembling cre are indicated by arrows. The major transcriptional start site of the lacR promoter is symbolized by a boldface arrow. Putative RNA polymerase- and ribosome-binding sites are underlined.