FIG. 3.
Effects of Ffh depletion on export of DsbA. Plasmid pNH5 (encoding SecM-Met6) was introduced into WAM113 (Para-ffh) cells, which were grown first in M9-amino acids-0.2% arabinose medium, washed three times with arabinose-free medium, and grown further in the same arabinose-free medium supplemented with 0.4% glucose. After 0 (lane 1), 5 (lane 2), 6 (lane 3), and 7 (lane 4) hours in the absence of arabinose, SecM-Met6 was induced with 5 mM cyclic AMP for 15 min and cells were pulse-labeled with [35S]methionine for 30 seconds. Samples were processed for OmpA, DsbA, and SecM immunoprecipitation as indicated. The DsbA sample was AMS modified before immunoprecipitation. SecM-Met6 band A represents the elongation-arrested translation product, the predominant cytosolic form of this protein (32).