Dual-Specificity Anti-sigma Factor Reinforces Control of Cell-Type Specific Gene Expression in Bacillus subtilis
Fig 3
Role of CsfB in the mother cell.
A: microarrays were used to assess the impact of mutational inactivation of the σG-dependent promoter for the csfB gene (PsigF strain) on sporulation-specific gene expression. The panel represents the percentage of genes in each of the sporulation-specific sigma regulons, whose expression was increased (green bars) or unaffected (grey bars) in the PsigF mutant relative to the wild type. Genes, repressed (“R”) by or dependent (“D”) on the following ancillary transcription factors, are shown: D, SpoIIID; R, GerR; VT, SpoVT; E, GerE. B: the panel illustrates the results of a fluorescence in situ hybridization (FISH) experiment to localize the sspE mRNA, produced under σG control, in a wild type strain and in the PsigF mutant. The mRNA was localized using a fluorescein-labelled anti-sense oligonucleotide and fluorescence microscopy. PC, phase contrast. The graph on the right shows the length (in μm) distribution of the fluorescence signal measured along the longitudinal axis of the cells. C: immunoblot analysis of pro-σK and σK. Samples from cultures of the wild type and PsigF-csfB strain were collected at the indicated times (in minutes) after the induction of sporulation by re-suspension. Whole cell extracts were prepared, proteins (15 μg) electrophoretically resolved and immunobloted with anti-σK and anti-σA (as a loading control) antibodies. Arrows indicate the position of pro-σK (in black) and σK (red).