FIG. 5.
Primer extension analysis of PsigD. A total of 50 μg of total RNA was isolated at T0 and subjected to primer extension analysis using primer OSPE2. In parallel, OSPE2 was utilized in a dideoxy sequencing reaction on plasmid pLM112, which contains the PsigD promoter region and the 5′ half of the sigD gene. Lanes of the sequencing reaction are indicated as G, A, T, and C. Lane 1, LMB1 (wild type); lane 2, LMB232 (PsigDΔ); lane 3, LMB233 (fla/che PAΔ PD-3Δ PsigDΔ); lane 4, LMB234 (fla/che PAΔ PD-3Δ PsigDΔ flgM::mini-Tn10). The +1 position for PsigD is indicated to the left. The sequence indicated corresponds to the template strand (i.e., it is complementary to the sequence indicated in Fig. 1). Lane 1 shows the primer extension product corresponding to the weakly expressed transcript that initiates at PsigD. Lanes 2 to 4 show that this product is absent in PsigDΔ strains.