Milestones in Bacillus subtilis sporulation research

Abstract

Endospore formation has been a rich field of research for more than a century, and has benefited from the powerful genetic tools available in Bacillus subtilis. In this review, we highlight foundational discoveries that shaped the sporulation field, from its origins to the present day, tracing a chronology that spans more than one hundred eighty years. We detail how cell-specific gene expression has been harnessed to investigate the existence and function of intercellular proteinaceous channels in sporulating cells, and we illustrate the rapid progress in our understanding of the cell biology of sporulation in recent years using the process of chromosome translocation as a storyline. Finally, we sketch general aspects of sporulation that remain largely unexplored, and that we envision will be fruitful areas of future research.

Asymmetric localization of the cell division machinery during Bacillus subtilis sporulation

“…A thinner septum could be beneficial during sporulation in two ways. First, several protein complexes are proposed to form channels across both septal membranes during sporulation, including SpoIIQ-SpoIIIAH and SpoIIIE ( Blaylock et al, 2004 ; Fleming et al, 2010 ; Meisner et al, 2008 ; Riley et al, 2021a ; Yen Shin et al, 2015 ). A thinner septum could facilitate interaction between the subunits located in the forespore and those in the mother cell.…”

A new role for SR1 from Bacillus subtilis: regulation of sporulation by inhibition of kinA translation

“…Rank 1 target was kinA encoding the major kinase of the sporulation phosphorelay that phosphorylates Spo0F (rev. in 26 ). IntaRNA ( 44 ) predicted 7 more or less continuous regions in kinA complementary with SR1 which we designated A’ to G’ in kinA and A to G in SR1, among them two stretches, G’ and F’, flanking the RBS, respectively (Figure 2 ) and one, E’, directly downstream of the GUG start codon.…”

“…Over the years, the complex regulatory network that governs sporulation and involves more than 500 of the 4200 B. subtilis genes ( 25 ) has been elucidated step by step (rev. in 26 ). Five histidine kinases, KinA, KinB, KinC, KinD and KinE, perceive and transmit environmental signals that finally result in phosphorylation of Spo0A, the central transcriptional regulator of the sporulation genes (rev.…”

Bacillus subtilis Histidine Kinase KinC Activates Biofilm Formation by Controlling Heterogeneity of Single-Cell Responses

“…As a result, biofilms—multicellular communities encased in the extracellular matrix—are formed ( 4 ). When starvation is prolonged, B. subtilis cells begin to form spores ( 5 ), which are metabolically inert and highly resistant to environmental stresses. In the starving community, growing, biofilm-forming, and sporulating cell types coexist ( 6 , 7 ), but the mechanisms controlling this heterogeneity are not fully uncovered.…”