FIG. 4.
Functionality of XphA and XqhA in the secretory process. (A) Proteolytic activities of strains derived from ΔPQ and ΔPQPAQA mutant strains on TSA-milk plates. (B) Immunoblotting of protein extracts from the strains described for panel A bearing either the empty vector pMMB190 (p190) or the pMMB-PAQA plasmid (PAQA) expressing xphA and xqhA genes in tandem. PAO1, wild-type strain; ΔPQ, PAO1 mutant deleted of xcpP and xcpQ; ΔPQPAQA, PAO1 mutant deleted of xcpP, xcpQ, xphA, and xqhA genes. Proteins were probed with antisera directed to LasB or β-lactamase (Bla) and revealed by chemiluminescence. C, cellular proteins; Ex, extracellular proteins.