FIG. 2.
Accumulation of RpoS in exponential- and stationary-phase wild-type and dnaK mutant cells. Western blots of total cell extracts of PBL500 (wild type) (A), PBL501 (ΔdnaK52) (B), and PBL504 (ΔdnaK52/pPtac::dnaK+J+) (C) probed with anti-RpoS monoclonal antisera. Lanes: 1 to 5, exponential phase (Fig. 1A, arrows 1 through 5); 6, onset of starvation; 7, 2 h after onset; 8, 4 h after onset; 9, 24 h after onset; 10, PBL503 (ΔmutS-rpoS458) 2 h after onset. (D) Densitometric analysis of the bands shown in panels A through C. Symbols: circles, PBL500; squares, PBL501; triangles, PBL504. Five micrograms of protein was loaded per lane. Blots were developed to achieve equivalent band intensity of a constant amount of an RpoS-containing extract (PBL504, lanes not shown). Signal intensity was linear within the range of detection as determined by regression analysis of PBL504 extracts (r2 = 0.99). The onset of glucose starvation is indicated by the arrow.