Figure 2.

pIII-N1^CTX disulfide bonds II and III are required for TolAIII^Vc interaction. A, schematic representation of disulfide bond localization (15) on the secondary structure of TolAIII^Vc and pIII-N1^CTX; B, representation of disulfide bonds on the crystal structure of the complex. Disulfide bonds in pIII-N1 are numbered I–IV and colored in red. Italic numbers refer to cysteine residue positions. C, oxidative bacterial two-hybrid assay: Oxi-BTH reporter cells producing the T25 domain fused to pIII-N1^CTX, pIII-N1N2^CTX, or pIII-N2^CTX domains and the T18 domain fused to V. cholerae TolAIII were spotted on MacConkey plates. Variants bearing substitutions aimed to abolish each of the four disulfide bonds in the pIII-N1^CTX domain (C32S, C47S, C75S, and C96S) or in TolAIII^Vc (C292S) are presented. TolAIII^Ec and pIII-N1^M13 are used as a controls. n.t., not tested.