FIG. 2.

Mapping the transcriptional start site of dadAB by primer extension. The sequence lanes have been oppositely labeled such that the coding strand sequence is denoted, although the actual reactions were performed with the primer extension primer (RJ800EXT) and is thus the noncoding strand. Below is a control extension reaction of the β-lactamase gene (blaP) also present on the plasmid to ensure equal loading. RJ800EXT hybridizes to plasmid pRJ800 downstream of the multiple cloning site; thus, the extended products shown are from the plasmid-borne promoter (pCB888) only. Total RNA was isolated from the strains grown in glucose-ammonium minimal medium supplemented with ampicillin (100 μg/ml) for plasmid maintenance and with alanine or IPTG as indicated. Lanes: 1, KC3821, no addition; 2, KC3821, supplemented with 0.2% l-alanine; 3, KC3848, no addition; 4, KC3848, supplemented with 1 mM IPTG.