FIG. 2.

Expression and partial purification of tagged XylS variants. (A) Immunoblot analysis of expression of XylS proteins in E. coli DH5α. Equal amounts of bacteria bearing the pBRSN217 series expression plasmids were used for preparation of the total lysates in Laemmli sample buffer after 2 h of induction with IPTG (isopropyl-β-d-thiogalactopyranoside). Total protein extracts were separated by SDS-PAGE (12%) and analyzed by immunoblotting with the 3F12 monoclonal antibody. The proteins are schematically depicted on Fig. 3. (B) Silver-stained SDS-PAGE (12%) analysis of wt N-XylS and ΔN209 proteins retained on the 3F12 beads. (C) Immunoblot analysis of wt N-XylS and ΔN209 proteins retained on the 3F12 beads. Proteins were separated by SDS-PAGE (12%) and analyzed by immunoblotting by using the 3F12 monoclonal antibody. wt N-XylS and ΔN209 proteins, as well as the light chain (IgG LC) and heavy chain (IgG HC) of the 3F12 monoclonal antibody eluted from the TSK beads are indicated with arrows.