Genome-wide transcriptional analysis of the phosphate starvation stimulon of 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

枯草芽孢杆菌（Bacillus subtilis）可通过激活PhoP调节子（PhoP regulon）与SigB调节子（SigB regulon）响应磷饥饿胁迫。其中PhoP调节子可对磷饥饿胁迫产生特异性响应，最大化从环境中获取无机磷酸盐（Pi）并降低细胞对该必需营养物质的需求；而SigB调节子则通过保护DNA、细胞膜等核心细胞组分，介导对各类胁迫的非特异性抗性。本研究借助DNA宏阵列（DNA macroarrays）在全基因组水平解析了枯草芽孢杆菌的磷饥饿胁迫响应机制。通过异常值分析与聚类分析相结合的方法，本研究筛选得到4个潜在的PhoP调节子新成员，分别为yfkN（2',3'-环核苷酸2'-磷酸二酯酶）、yurI（核糖核酸酶）、yjdB（功能未知）以及vpr（胞外丝氨酸蛋白酶）。据推测，YurI可介导RNA的非特异性降解；而YfkN对多种核苷酸磷酸的催化活性表明，其可作用于YurI降解RNA所释放的3'或5'磷酸核糖核苷酸底物。上述潜在的PhoP调节子新成员要么已被证实、要么经预测可被分泌，且极有可能在环境中从各类有机磷源回收无机磷酸盐的过程中发挥关键作用。关键词：其他