FIG 2.

Cells lacking the ω factor have altered RNAP composition and individual subunit stability. Free or complex-bound subunits were separated according to their molecular masses via size selection before analysis using mass spectrometry. (A) In the >100-kDA fraction only large RNAP subunits (β and β′) and subunits within the RNAP complex should be found. (B) Data were validated by Western blotting using a β subunit antibody. (C) Protein degradation in the ΔrpoZ strain is highlighted by the presence of larger subunits within the <30-kDa fraction. (D) Transcriptional changes as a cause of alterations in RNAP composition were excluded by analyzing expression of RNAP genes from RNA sequencing data sets. Shown are the fold changes for each RNAP gene in the mutant strain compared to the wild type. Where relevant, error bars show SEM. Statistical significance was determined using Student's t test (*, P < 0.05; **, P < 0.01).