A previously unidentified σ factor and two accessory proteins regulate oxalate decarboxylase expression in Bacillus subtilis

Abstract

SummaryWe have investigated the function of a cell envelope stress-inducible gene, yvrI, which encodes a 22.5 kDa protein that includes a predicted s 70 region 4 domain, but lacks an apparent region 2 domain. YvrI interacts with RNA polymerase and overexpression of YvrI results in induction of OxdC, an oxalate decarboxylase maximally expressed under low-pH conditions. We have used microarray-based analyses to define the YvrI regulon. YvrI is required for the transcription of three operons (oxdC-yvrL, yvrJ and yvrI-yvrHa) each of which is preceded by a highly similar promoter sequence. Activation of these promoters requires both YvrI and the product of the second gene in the yvrI-yvrHa operon, YvrHa. YvrI and YvrHa together allow recognition of the oxdC promoter, stimulate DNA melting and activate transcription by core RNA polymerase. Together, these results suggest that YvrI is a previously unrecognized s factor in Bacillus subtilis and that the 9.5 kDa YvrHa protein acts as a required co-activator of transcription. A yvrL deletion results in the upregulation of YvrI activity suggesting that YvrL is a negative regulator of YvrI-dependent transcription, possibly functioning as an anti-s factor.

The atypical two-subunit σ factor from Bacillus subtilis is regulated by an integral membrane protein and acid stress

“…The B. subtilis SigO-RsoA proteins constitute an atypical two-subunit s factor (MacLellan et al, 2008(MacLellan et al, , 2009a that is activated in response to certain cell-wall-acting antibiotics and to growth under acidic conditions (Cao et al, 2002;Hachmann et al, 2009;MacLellan et al, 2009b). In this communication, we identify the protein encoded by gene rsiO as the cognate anti-s factor to SigO-RsoA.…”

“…1a) (MacLellan et al, 2008(MacLellan et al, , 2009a. Previous work demonstrated that deletion of the gene downstream of oxdC (rsiO, formerly yvrL) resulted in an increase in basal SigO-RsoA activity (MacLellan et al, 2008) and increased OxdC accumulation in B. subtilis cells (MacLellan et al, 2009b) suggesting that RsiO, a predicted membrane protein (Fig.…”

“…rsiO expression is driven from a promoter upstream of oxdC, but an attenuator sequence located between the ORFs (Fig. 1a) reduces rsiO transcription relative to oxdC transcription (MacLellan et al, 2008). In this work, we have explored the molecular basis for RsiO inhibitory activity on SigO-RsoA function by reconstituting the SigO-RsoA-RsiO regulatory system into E. coli.…”

“…1a, b) is predicted to encode a membrane spanning protein. It was previously shown that the deletion of rsiO increased basal activity of SigO-RsoA activity in B. subtilis under non-inducing conditions (MacLellan et al, 2008), and also resulted in the increased accumulation of another regulon member protein, OxdC (MacLellan et al, 2009b), suggesting that rsiO encoded a negative regulator of SigO-RsoA activity.…”

“…SigO-RsoA is an atypical two-subunit s factor from B. subtilis (MacLellan et al, 2008(MacLellan et al, , 2009a. Both proteins possess sequence similarity to the ECF s 70 family of proteins, interact with each other and with RNAP subunits, and are required for the initiation of transcription from a set of related promoters in the B. subtilis genome (MacLellan et al, 2009a, b).…”