Modulation of extracytoplasmic function sigma factor promoter selectivity by spacer region sequence

The ability of bacteria to adapt to stress depends on their ability to conditionally express specific sets of genes. Bacillus subtilis encodes seven extracytoplasmic function (ECF) sigma (σ) factors that regulate functions important for survival under conditions eliciting cell envelope stress. Of these, four have been studied in detail: σM, σW, σX and σV . The regulons of these four σ factors overlap, although the sequences that determine promoter selectivity are incompletely understood. A major role in promoter selectivity has been ascribed to the core promoter -10 and -35recognition elements. Here, we demonstrate that a homopolymeric T-tract motif, proximal to the-35 recognition element, functions in combination with the core promoter sequences to2determine selectivity for ECF sigma factors. This motif is critical for promoter activation by σV, contributes to activation by σM and σX, but has relatively little effect for σW. We propose that this motif, which is a feature of the deduced promoter consensus for a subset of ECF s factors from many species, affects confirmation or curvature of the DNA to influence promoter activity. The differential effect of this region amongst ECF s factors thereby provides a mechanism to modulate the nature and extent of regulon overlap. Two-condition experiment (with or without IPTG induction of sigV), in WT or strain lacking all 7 ECF sigma factor Please note that the complete_normalized_data.txt contains the data for control probes (resulting in 4,128 data rows).