Proc. Natl Acad. Sci. USA 116, 14228–14237 (2019)

Bacterial spores are highly durable and resilient cells that are dormant during periods of stress. Nutrient binding to cognate receptors in the spore membrane induces germination, restarting cellular activity. Seeking to understand the signaling pathways that are triggered during germination of Bacillus subtilis, Zhou et al. profiled Arg phosphorylation, which is mediated by the kinase McsB and the phosphatase YwlE. Deletion of mcsB or ywlE had an opposite effect, increasing or decreasing germination efficiency, respectively, indicating the importance of Arg dephosphorylation during this process. Phosphoproteomic analysis identified 18 phospho-Arg sites enriched in spores lacking YwlE, including the translational factor Tig and the housekeeping σ factor SigA. An R45D variant of Tig that mimics constitutive phosphorylation stalls germination, impairs protein synthesis, and disrupts Tig association with the ribosome. Analogously, an R365D variant of SigA prevents restoration of transcription, likely by interfering with DNA binding. Although phosphorylation of Tig and SigA alone are not sufficient to halt germination, their effects, along with those of ywlE deletion, point to a central role for YwlE in signaling during this process.