Cell envelope gene expression in phosphate-limited Bacillus subtilis cells

Abstract

The high phosphate content of Bacillus subtilis cell walls dictates that cell wall metabolism is an important feature of the PhoPR-mediated phosphate limitation response. Here we report the expression profiles of cell-envelope-associated and PhoPR regulon genes, determined by live cell array and transcriptome analysis, in exponentially growing and phosphate-limited B. subtilis cells. Control by the WalRK two-component system confers a unique expression profile and high level of promoter activity on the genes of its regulon with yocH and cwlO expression differing both qualitatively and quantitatively from all other autolysin-encoding genes examined. The activity of the PhoPR two-component system is restricted to the phosphate-limited state, being rapidly induced in response to the cognate stimulus, and can be sustained for an extended phosphate limitation period. Constituent promoters of the PhoPR regulon show heterogeneous induction profiles and very high promoter activities. Phosphate-limited cells also show elevated expression of the actin-like protein MreBH and reduced expression of the WapA cell wall protein and WprA cell wall protease indicating that cell wall metabolism in this state is distinct from that of exponentially growing and stationary-phase cells. The PhoPR response is very rapidly deactivated upon removal of the phosphate limitation stimulus with concomitant increased expression of cell wall metabolic genes. Moreover expression of genes encoding enzymes involved in sulphur metabolism is significantly altered in the phosphate-limited state with distinct perturbations being observed in wild-type 168 and AH024 (DphoPR) cells.

Genome-Wide Analysis of Phosphorylated PhoP Binding to Chromosomal DNA Reveals Several Novel Features of the PhoPR-Mediated Phosphate Limitation Response in Bacillus subtilis

“…Transcriptome and proteome analyses show that large numbers of genes are differentially expressed when E. coli and B. subtilis cells become phosphate limited, demonstrating that cellular adaptation to this condition requires significant physiological change (5)(6)(7)(8)(9)(10). Moreover, the PhoBR and PhoPR regulons in E. coli and B. subtilis show several similarities.…”

“…Moreover, the PhoBR and PhoPR regulons in E. coli and B. subtilis show several similarities. In E. coli activated PhoBϳP directly regulates expression of 31 genes in 9 transcription units, while in B. subtilis PhoPϳP directly regulates expression of 34 genes in 13 transcription units (1,7,9,11). The genes of both regulons encode proteins involved in phosphorous assimilation (e.g., phosphate transporters and phosphodiesterases) and the regulators of their expression (i.e., PhoBR and PhoPR) (1,7,9,11).…”

“…In E. coli activated PhoBϳP directly regulates expression of 31 genes in 9 transcription units, while in B. subtilis PhoPϳP directly regulates expression of 34 genes in 13 transcription units (1,7,9,11). The genes of both regulons encode proteins involved in phosphorous assimilation (e.g., phosphate transporters and phosphodiesterases) and the regulators of their expression (i.e., PhoBR and PhoPR) (1,7,9,11). However, due to the large phosphorous content of WTA and LTA, the B. subtilis regulon has a major cell wall component through PhoPR-mediated regulation of expression of teichoic (TagAB) and teichuronic (TuaA-H) acid synthetic enzymes (2,4,9).…”

“…However, due to the large phosphorous content of WTA and LTA, the B. subtilis regulon has a major cell wall component through PhoPR-mediated regulation of expression of teichoic (TagAB) and teichuronic (TuaA-H) acid synthetic enzymes (2,4,9). Thus, when B. subtilis cells become phosphate limited, PhoPϳP represses tagAB and activates tuaA-H expression (7,9,12,13,14). Teichuronic acid is a non-phosphate-containing anionic polymer that replaces teichoic acid in the wall of phosphate-limited cells.…”

“…The genes of both regulons encode proteins involved in phosphorous assimilation (e.g., phosphate transporters and phosphodiesterases) and the regulators of their expression (i.e., PhoBR and PhoPR) (1,7,9,11). However, due to the large phosphorous content of WTA and LTA, the B. subtilis regulon has a major cell wall component through PhoPR-mediated regulation of expression of teichoic (TagAB) and teichuronic (TuaA-H) acid synthetic enzymes (2,4,9). Thus, when B. subtilis cells become phosphate limited, PhoPϳP represses tagAB and activates tuaA-H expression (7,9,12,13,14).…”