Upper panel: Alignment of M. tuberculosis S18-1 and S18-2 protein sequences. Peptide sequences used to raise polyclonal antibodies are underlined.
Lower panel: S18 proteins dialyzed against EDTA or 10 μM ZnSO4 were titrated into a fluorescently labeled S6 protein. Binding curves are shown as a fraction of S6 bound to S18-1 in presence of Zn2+
(A) or S18-2 in presence of EDTA (B)
Of note, we tested both His-tagged and the untagged versions of the S18 proteins and found that the tag did not affect binding to S6 over the range of protein concentrations relevant for the MST assays. Binding curves of the untagged S18 proteins are shown here.