Fig. 2

Agglutination assay of fimA mutant bacterial derivatives. A schematic representation of the agglutination assay: A A suspension of Saccharomyces cerevisiae cells (yellow) was spread together with bacteria (blue) on a glass plate. B Bacteria adhering to yeast cells by virtue of the FimH fimbriae subunit that recognizes mannose residues on the surface of yeast cells. C The polyvalent binding of fimbriated bacteria to yeast cells causes an agglutination chain reaction, which is macroscopically visible. Photographic images of agglutination reaction tests performed with the following bacterial strains: D WT E. coli, E) Shigella flexneri M90T (negative control), F Stop codon mutant (fimA_A106T) E. coli, G E. coli ΔfimA₇₅, H E. coli ΔfimA₇₅::L3S2P56 and I E. coli ΔfimA₁::L3S2P56. Plasmid trans-complementation of fimA mutant derivatives. As illustrated in the schematic circular plasmid map, the fimA⁺ allele was expressed from a P15 plasmid derivative under control of the lac promoter (orange). The empty vector, pSU19, was used as negative control. Agglutination reaction for the following strains: J WT E. coli + empty vector, K WT E. coli + fimA⁺ plasmid, L E. coli fimA_A106T + empty vector, M E. coli fimA_A106T + fimA⁺ plasmid, N E. coli ΔfimA₇₅ + empty vector, O E. coli ΔfimA₇₅ + fimA⁺ plasmid, P E. coli ΔfimA₇₅::L3S2P56 + empty vector, Q E. coli ΔfimA₇₅::L3S2P56 + fimA⁺ plasmid, R E. coli ΔfimA₁::L3S2P56 + empty vector, S E. coli ΔfimA₁::L3S2P56 + fimA⁺ plasmid. Scale bars D–S: 2 cm.