Bacterial spores can remain dormant for years but possess the remarkable ability to germinate, within minutes, once nutrients become available. However, it still remains elusive how such instant awakening of cellular machineries is achieved. UtilizingBacillus subtilisas a model, we show that YwlE arginine (Arg) phosphatase is crucial for spore germination. Accordingly, the absence of the Arg kinase McsB accelerated the process. Arg phosphoproteome of dormant spores uncovered a unique set of Arg-phosphorylated proteins involved in key biological functions, including translation and transcription. Consequently, we demonstrate that during germination, YwlE dephosphorylates an Arg site on the ribosome-associated chaperone Tig, enabling its association with the ribosome to reestablish translation. Moreover, we show that Arg dephosphorylation of the housekeeping σ factor A (SigA), mediated by YwlE, facilitates germination by activating the transcriptional machinery. Subsequently, we reveal that transcription is reinitiated at the onset of germination and its recommencement precedes that of translation. Thus, Arg dephosphorylation elicits the most critical stages of spore molecular resumption, placing this unusual post-translational modification as a major regulator of a developmental process in bacteria.

The Gram positive bacterium Bacillus subtilis and its relatives are capable of forming a durable dormant long-lasting spore. Although spores can remain dormant for years, they possess the remarkable capacity to rapidly resume life and convert into actively growing cells. This cellular transition initiates with a most enigmatic irreversible event, termed germination, lasting only for a few minutes. Germination is typified by a morphological conversion that culminates in loss of spore resilient properties. Yet, the molecular events occurring during this brief critical phase are largely unknown. The current widely accepted view considers germination to occur without the need for any macromolecule synthesis; however, accumulating data from our laboratory and others, highlighted here, provide evidence that both transcription and translation occur during germination and are required for its execution. We further underline numerous overlooked studies, conducted mainly during the 1960s-70s, reinforcing this notion. We propose to revisit the fascinating process of spore germination and redefine it as a pathway involving macromolecule synthesis. We expect our perspective to shed new light on the awakening process of a variety of spore-forming environmental, commensal and pathogenic bacteria and possibly be applicable to additional organisms displaying a quiescent life form.