FIG. 4.

Identification of differentially abundant proteins in the Δhfq knockout mutant. (A) Total proteins of logarithmically grown wild-type strain MC58 and the Δhfq mutant were separated by 2D gel electrophoresis. Proteins were first focused on a nonlinear pH 3 to 10 gradient and then separated on a 9 to 16.5% SDS-polyacrylamide gel. Cells were grown to an OD₆₀₀ of 0.5 in GC broth. (B) 1D SDS-PAGE analysis of total proteins (Total) or cytoplasmic (Cyto) or envelope (Env1 and Env2) fractions of cells of the wild type (lane +) and the Hfq mutant (lane −) grown to log phase in GC broth. Both 1D and 2D gels were stained with Coomassie brilliant blue R-250. In addition, wild-type and Hfq mutant cultures were grown to an OD₆₀₀ of 0.2 in Mueller-Hinton medium containing 0.25% glucose, and 22 ml of cell-free supernatant was precipitated and loaded (Supr).