Reversible protein phosphorylation is an important and ubiquitous protein modification in all living cells. Here we report that protein phosphorylation on arginine residues plays a physiologically significant role. We detected 121 arginine phosphorylation sites in 87 proteins in the Gram-positive model organism Bacillus subtilis in vivo. Moreover, we provide evidence that protein arginine phosphorylation has a functional role and is involved in the regulation of many critical cellular processes, such as protein degradation, motility, competence, and stringent and stress responses. Our results suggest that in B. subtilis the combined activity of a protein arginine kinase and phosphatase allows a rapid and reversible regulation of protein activity and that protein arginine phosphorylation can play a physiologically important and regulatory role in bacteria.McsB | YwlE | ClpC | HSP100/Clp | phosphagen kinase

The soil bacterium Bacillus subtilis possesses a fine-tuned and complex heat stress response system.

SummaryWhereas about 70 small non-coding RNAs have been found in the Escherichia coli genome, relatively little is known about regulatory RNAs from Gram-positive bacteria. Here, we demonstrate that the recently identified small untranslated RNA SR1 from the Bacillus subtilis genome is a regulatory RNA involved in finetuning of arginine catabolism. 2D protein gel electrophoresis indicated three possible SR1 targets that are regulated by the transcriptional activator AhrC, which was shown to be the primary target of SR1. In vitro pairing studies and an in vivo reporter gene test demonstrated a specific interaction between SR1 and ahrC mRNA. This interaction did not lead to degradation of ahrC mRNA, but inhibited translation at a postinitiation stage. Our data show that the Hfq chaperone was not required for the stabilization of SR1 in vivo.

SummaryThe Bacillus subtilis clpP gene, encoding the proteolytic component of the Clp or Ti protease, was cloned and sequenced. The amount of clpP-specific mRNA increased after heat shock, salt and ethanol stress, as well as after treatment with puromycin. Two transcriptional start sites upstream of the clpP structural gene were identified, preceded by sequences resembling the consensus sequences of promoters recognized by A

Cells of the soil bacterium Bacillus subtilis have to adapt to fast environmental changes in their natural habitat. Here, we characterized a novel system in which cells respond to heat shock by regulatory proteolysis of a transcriptional repressor CtsR. In B. subtilis, CtsR controls the synthesis of itself, the tyrosine kinase McsB, its activator McsA and the Hsp100/Clp proteins ClpC, ClpE and their cognate peptidase ClpP. The AAA+ protein family members ClpC and ClpE can form an ATP‐dependent protease complex with ClpP and are part of the B. subtilis protein quality control system. The regulatory response is mediated by a proteolytic switch, which is formed by these proteins under heat‐shock conditions, where the tyrosine kinase McsB acts as a regulated adaptor protein, which in its phosphorylated form activates the Hsp100/Clp protein ClpC and targets the repressor CtsR for degradation by the general protease ClpCP.