Fig. 4.

Silver-stained SDS/PAGE gel showing that the immunity proteins specific for enterocin P and sakacin A form complex with the man-PTS components only in the presence of their cognate bacteriocins. L. sakei clones: B502 expressing fentiP, B503 expressing fsaiA, B507 expressing empty vector; B244 is a lactococcal strain expressing lcnA and flciA. Protein samples were purified from cultures grown in the absence (−) or presence (+) of added bacteriocins (≈50 BU/ml for enterocin P in B502+ and 25 BU/ml for sakacin A in B503+). Arrowheads signify the man-PTS components (IIAB, IIC, and IID) and the immunity proteins (Im: fLciA in B244, fEntiP in B502, and fSaiA in B503); M; molecule weight protein markers. Equal volumes of the eluted fractions (each 5 μl of total 100 μl) were applied to wells for direct comparison.