FIG. 1.

Mapping the purD promoter by exonuclease III deletions. The structure of the purDEK region from L. lactis is shown on the top. Filled boxes correspond to the structural genes, and the open box corresponds to a putative −10 region. The localizations of DNA fragments present in the promoter probe plasmid pAK80 are shown below the physical map and are labelled by the plasmid designation. The Lac-positive (+) or -negative (−) phenotype (defined by the presence or absence, respectively, of blue color development on DN medium agar plates containing X-Gal) was analyzed in MG1363 transformants of the respective plasmid.