Fig 6.

Orientation of the invertible fim promoter in CFT073 MMR mutants. The promoter orientation was determined by λ red PCR amplification of the invertible element, followed by digestion using SnaB1. Asymmetric cutting of SnaB1 revealed the orientation of the invertible element; phase ON is indicative of the expression of type 1 fimbriae, and phase OFF is indicative of blocked type 1 fimbrial expression. The “+” and “−” signs represent the fim L-ON status of CFT073 background; “+” represents CFT073 fim L-ON, and “−” represents CFT073 wild type.