Figure 1.

Strategy for gene inactivation and complementation of rpoN (a) and rpoS (b) in 297. rpoN and rpoS (black solid boxes) were first cloned in pGEM-T (pALH364 and pALH362, respectively). Only the relevant portions of the plasmids are shown (labeled at the left). rpoN and rpoS were insertionally disrupted with ermC (diagonal stripes) (pALH394 and pALH386, respectively). For complementation of rpoN, suicide plasmid pALH400 was constructed as described in Materials and Methods. Relevant restriction sites are shown, and relevant promoters are indicated by light gray boxes. Short arrows denote primers used for PCR (Table 2).