FIG. 2.

Stability of PrgJ in wild-type and type III secretion-deficient strains. Cultures of the wild type and the invA mutant containing a plasmid carrying prgJ under control of an arabinose-inducible promoter were grown in Luria-Bertani broth (0.3 M NaCl) containing 0.02% arabinose to an OD₆₀₀ of 0.8. Chloramphenicol was added to a final concentration of 60 μg/ml, and 1-ml aliquots were removed and precipitated by the addition of TCA as described for Fig. 1. Pellets were loaded on sodium dodecyl sulfate-12% polyacrylamide gels, transferred to nitrocellulose, and incubated with anti-PrgJ serum followed by anti-rabbit goat horseradish peroxidase-conjugated antibody. Bands were detected by chemiluminescence. Aliquots were withdrawn 0, 5, 10, 15, 30, and 60 min after the addition of chloramphenicol.