Fig. 1

Overexpression and purification of MucA’ and MucB proteins. Proteins from samples corresponding to 20 μl of bacterial cultures or equivalent amount of protein from the purification steps were separated on a 12% SDS-polyacrylamide gel and stained with Coomassie Brilliant Blue R 250. Lane ST, molecular weight markers; lane 1, culture of the strain BL21(DE3)/pYG8506 (MucA’) before induction; lane 2, culture of the strain BL21(DE3)/pYG8506 (MucA’) after induction; lane 3, the purified MucA’ protein after gel filtration on a Superdex XK 16/60 column; lane 4, culture of the strain BL21(DE3)/pLysS+pYG8512 (MucB) before induction; lane 5, culture of the strain BL21(DE3)/pLysS+pYG8512 (MucB) after induction; lane 6, denatured MucB protein prior to refolding by gel filtration; line 7, the purified MucB protein (peak fraction after refolding by gel filtration)