FIG. 1.

Insertion-duplication mutagenesis of htrA in strain USA0352/78. (A) Diagram of insertion-duplication mutagenesis showing homologous recombination between the K. pneumoniae chromosome of wild-type strain USA0352/78 and the pHTRAI disruption construct to generate isogenic htrA mutant USA0352-htrA⁻. DNA fragment size in the diagram is not to scale. The line in the mutant genome represents the plasmid DNA integrated into the chromosome. Black boxes, EcoRV-HindII htrA internal fragment cloned in pHTRAI and used as probe in the Southern blot analysis. Expected sizes (kilobases) of the fragments that hybridize with the probe described above are indicated. (B) Southern blot analysis of K. pneumoniae wild-type and htrA mutant chromosomes digested with EcoRI. Molecular size markers (kilobases) are shown on the left.