FIG. 2.

Characterization of the bphA1 promoter. (A) DNA probes used for RNA slot blot hybridization. A 1.1-kb KpnI fragment (probe 1), a 0.9-kb EcoRI-HincII fragment (probe 2), and a 0.7-kb HincII-BamHI fragment (probe 3) of the bphA1 upstream region were used to localize the promoter region of bphA1. The position of the 1.4-kb XhoI-BamHI fragment containing the bphA1 promoter is indicated by a line below the physical map. (B) RNA slot blot hybridization analysis of bphA1 transcripts in Rhodococcus sp. strain RHA1. Two micrograms of total RNA from RHA1 cells grown in LB medium or on a substrate as a sole source of carbon in W minimal medium was blotted onto a nylon membrane and hybridized with digoxigenin-labeled probes 1, 2, and 3.