Fig 3.

Representation of the pilC1 and pilC2 loci of K. kingae strain KK03 derivatives used in this study. The pilC1 and pilC2 genes are present at separate loci in the genome. The ΔpilC1 and ΔpilC2 mutants are marked with a tetracycline resistance cassette (Tet^r) and a kanamycin resistance cassette (Kan^r), respectively. Both deletion mutations were combined to generate the ΔpilC1 ΔpilC2 double mutant. ΔpilC2 PilC1D930A and ΔpilC2 PilC1D930K strains, with a ΔpilC2 PilC1mark strain (WT pilC1 with an erythromycin resistance cassette [Erm^r] upstream of the promoter region) used as a control, were generated to study the role of the PilC1 Ca-binding site in the absence of pilC2. ΔpilC1 PilC2D1444A and ΔpilC1 PilC2D1444K strains, with a ΔpilC1 PilC2mark strain (WT pilC2 with the Kan^r marker immediately downstream of pilC2) used as a control, were generated to study the role of the PilC2 Ca-binding site in the absence of pilC1. Mutations were combined to generate PilC1D930A PilC2D1444A and PilC1D930K PilC2D1444K strains.