Direct Regulation ofBacillus subtilis phoPRTranscription by Transition State Regulator ScoC

Abstract

Induction of the Pho response in Bacillus subtilis occurs when the P i concentrations in the growth medium fall below 0.1 mM, a condition which results in slowed cellular growth followed by entry into stationary phase. The phoPR promoter region contains three A -responsive promoters; only promoter P A4 is PhoP autoregulated. Expression of the phoPR operon is postexponential, suggesting the possibility of a repressor role for a transition-state-regulatory protein(s). Expression of a phoPR promoter-lacZ fusion in a scoC loss-of-function mutant strain grown in low-phosphate defined medium was significantly higher than expression in the wild-type strain during exponential growth or stationary phase. Derepression in the scoC strain from a phoP promoter fusion containing a mutation in the CcpA binding site (cre1) was further elevated approximately 1.4-fold, indicating that the repressor effects of ScoC and CcpA on phoP expression were cumulative. DNase I footprinting showed protection of putative binding sites by ScoC, which included the ؊10 and/or ؊35 elements of five (P B1 , P E2 , P A3 , P A4 , and P A6 ) of the six promoters within the phoPR promoter region. P A6 was expressed in vivo from the phoP cre1 promoter fusion in both wild-type and scoC strains. Evidence for ScoC repression in vivo was shown by primer extension for P A4 and P A3 from the wild-type promoter and for P A4 and P E2 from the phoP cre1 promoter. The latter may reflect ScoC repression of sporulation that indirectly affects phoPR transcription. ScoC was shown to repress P A6 , P A4 , P E2 , and P B1 in vitro.

Analysis of a bac operon-silenced strain suggests pleiotropic effects of bacilysin in Bacillus subtilis

“…PhoPR is another two-component response regulator in B. subtilis, regulating phosphate metabolism. PhoPR is subjected to cumulative repression by ScoC and CcpA (Kaushal et al, 2010). In our work, phoP transcript abundance was found to be 1.7 times higher in OGU1.…”

The Pho regulon: a huge regulatory network in bacteria

“…The Pi signal transduction network in this bacterium includes a positive feedback loop between the PhoP–PhoR and ResD–ResE two-component systems ( Schau et al, 2004 ). Alternative players such as the Spo0B–Spo0A two-component system, the AbrB and ScoC transition state regulators and an intermediate of the teichoic acid synthesis pathway are also involved in this network ( Hulett, 1996 ; Sun et al, 1996 ; Kaushal et al, 2010 ; Botella et al, 2014 ). ResD activates genes involved in both aerobic and anaerobic respiration, including two terminal oxidase genes.…”

“…Actually, a resD – abrB double mutant shows no Pho induction and resembles the phenotype of a phoPR mutant strain ( Hulett et al, 1994 ). The other transition state regulator involved in the network (ScoC), contrary to AbrB, produces a negative effect on the expression of phoPR ( Kaushal et al, 2010 ). This negative effect is accumulative with the one ejected by another B. subtilis regulator, CcpA, which is involved in carbon metabolism ( Puri-Taneja et al, 2006 ; see below).…”

Two Distinct Regulatory Systems Control Pulcherrimin Biosynthesis inBacillus subtilis

“…2AB). Genes controlled by TSRs tend to have low expression during exponential phase and higher expression as cells transition into stationary phase [2,10,31,[35][36][37]. We hypothesized that the effect of scoC and abrB disruption would cause increased pulcherrimin production as cells transition into stationary phase while cells without pchR would have higher pulcherrimin production during exponential phase.…”