Fig 4.

Wild-type NodD1 forms homodimers with wild-type NodD1 and heterodimers with mutant NodD1. β-Galactosidase activity (Miller units) of a lacZ reporter in cya mutant E. coli BTH101 expressing the indicated fusions to the T18 and T25 cya subdomains is shown. Interaction between NodD1 monomers reconstitutes active Cya and results in increased β-galactosidase activity. Each of the T25-NodD1 fusions interacts with each of the T18-NodD1 fusions. None of the T25 fusions interact with the T18 catalytic subdomain alone. Only the T25-zip fusion interacts with T18-zip.