Spo0A-Dependent Activation of an Extended −10 Region Promoter in Bacillus subtilis

Abstract

At the onset of endospore formation in Bacillus subtilis the DNA-binding protein Spo0A directly activates transcription from promoters of about 40 genes. One of these promoters, Pskf, controls expression of an operon encoding a killing factor that acts on sibling cells. AbrB-mediated repression of Pskf provides one level of security ensuring that this promoter is not activated prematurely. However, Spo0A also appears to activate the promoter directly, since Spo0A is required for Pskf activity in a ⌬abrB strain. Here we investigate the mechanism of Pskf activation. DNase I footprinting was used to determine the locations at which Spo0A bound to the promoter, and mutations in these sites were found to significantly reduce promoter activity. The sequence near the ؊10 region of the promoter was found to be similar to those of extended ؊10 region promoters, which contain a TRTGn motif. Mutational analysis showed that this extended ؊10 region, as well as other base pairs in the ؊10 region, is required for Spo0A-dependent activation of the promoter. We found that a substitution of the consensus base pair for the nonconsensus base pair at position ؊9 of Pskf produced a promoter that was active constitutively in both ⌬abrB and ⌬spo0A ⌬abrB strains. Therefore, the base pair at position ؊9 of Pskf makes its activity dependent on Spo0A binding, and the extended ؊10 region motif of the promoter contributes to its high level of activity.

Bacillus subtilis RNA Polymerase Recruits the Transcription Factor Spo0A∼P to Stabilize a Closed Complex during Transcription Initiation

“…Given the sequence similarity this mechanism will likely operate at the spoIIE promoter as well. However, other promoters such as the skf promoter which is activated by a low concentration of Spo0A 13,54 and σ H -dependent promoters where the 0A boxes are in different orientations compared to those at the spoIIG promoter may be activated by different mechanisms.…”

Cannibalism stress response in Bacillus subtilis

“…SDP is encoded in the sdpABC operon and repressed by AbrB during the exponential growth phase and in times of nutrient availability (Chen et al, 2006;Fujita et al, 2005). Upon entry into the stationary phase, repression by AbrB is released by active Spo0A and transcription of the corresponding genes is triggered.…”

Just-in-Time Control of Spo0A Synthesis in Bacillus subtilis by Multiple Regulatory Mechanisms

“…It was suggested that such arrays may form in the regulatory region for genes such as spoIIA, spoIIE, and spoIIG that exhibit multiple 0A boxes in tandem extending far upstream from the start site of transcription. That said, the mechanism by which Spo0AϳP activates transcription remains largely unclear, with few examples that have been well characterized, two for promoters recognized by A RNA polymerase (P spoIIG and P skf ) (10,26) and one (P spo0F ) for promoters recognized by H RNA polymerase (2).…”