Figure 4.

(a) Membrane protein expression of WcaJ_Cysless. Ten μg of total membrane preparations from E. coli DH5α cells expressing WcaJ (pLA3) and WcaJ_CysLess (pSEF102), both engineered with an N-terminal FLAG tag, were separated by 14% SDS-PAGE and detected by immunoblotting using 1:10,000 dilution of anti-FLAG M2 monoclonal antibody. L, molecular mass protein ladder. (b) Complementation of colanic acid production in E. coli XBF1(pWQ499). Bacteria expressing full length WcaJ (pLA3), WcaJ_CysLess (pSEF102) or containing the vector control (pBADNTF) were plated on LB agar supplemented with antibiotics, as needed, and 0.2% (w/v) arabinose. Colonies were evaluated for mucoid phenotype after 24 h.