Genome-wide transcriptional analysis of the phosphate starvation stimulon of Bacillus subtilis. Bacillus subtilis

Bacillus subtilis responds to phosphate starvation stress by inducing the PhoP and SigB regulons. While the PhoP regulon provides a specific response to phosphate starvation stress, maximizing the acquisition of phosphate (Pi) from the environment and reducing the cellular requirement for this essential nutrient, the SigB regulon provide non-specific resistance to stress by protecting essential cellular components such as DNA and membranes. We have characterized the phosphate starvation stress response of B. subtilis at a genome-wide level using DNA macroarrays. A combination of outlier and cluster analyses identified putatively new members of the PhoP regulon, namely yfkN (2',3'-cyclic-nucleotide 2'-phosphodiesterase), yurI (ribonuclease), yjdB (unknown) and vpr (extracellular serine protease). YurI is thought to be responsible for the non-specific degradation of RNA, whilst the activity of YfkN on various nucleotide phosphates suggests that it could act on substrates liberated by YurI which produces 3` or 5` phosphoribonucleotides. The putative new PhoP regulon members are either known or predicted to be secreted and are likely to be important for the recovery of inorganic phosphate from a variety of organic sources of phosphate in the environment. Keywords: other