Dataset Information

Developmentally-regulated excision of the SP? prophage reconstitutes a gene required for spore envelope maturation in Bacillus subtilis.

ABSTRACT: Temperate phages infect bacteria by injecting their DNA into bacterial cells, where it becomes incorporated into the host genome as a prophage. In the genome of Bacillus subtilis 168, an active prophage, SP?, is inserted into a polysaccharide synthesis gene, spsM. Here, we show that a rearrangement occurs during sporulation to reconstitute a functional composite spsM gene by precise excision of SP? from the chromosome. SP? excision requires a putative site-specific recombinase, SprA, and an accessory protein, SprB. A minimized SP?, where all the SP? genes were deleted, except sprA and sprB, retained the SP? excision activity during sporulation, demonstrating that sprA and sprB are necessary and sufficient for the excision. While expression of sprA was observed during vegetative growth, sprB was induced during sporulation and upon mitomycin C treatment, which triggers the phage lytic cycle. We also demonstrated that overexpression of sprB (but not of sprA) resulted in SP? prophage excision without triggering the lytic cycle. These results suggest that sprB is the factor that controls the timing of phage excision. Furthermore, we provide evidence that spsM is essential for the addition of polysaccharides to the spore envelope. The presence of polysaccharides on the spore surface renders the spore hydrophilic in water. This property may be beneficial in allowing spores to disperse in natural environments via water flow. A similar rearrangement occurs in Bacillus amyloliquefaciens FZB42, where a SP?-like element is excised during sporulation to reconstitute a polysaccharide synthesis gene, suggesting that this type of gene rearrangement is common in spore-forming bacteria because it can be spread by phage infection.

SUBMITTER: Abe K

PROVIDER: S-EPMC4191935 | biostudies-literature | 2014 Oct

REPOSITORIES: biostudies-literature

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Developmentally-regulated excision of the SPβ prophage reconstitutes a gene required for spore envelope maturation in Bacillus subtilis.

Abe Kimihiro K Kawano Yuta Y Iwamoto Keito K Arai Kenji K Maruyama Yuki Y Eichenberger Patrick P Sato Tsutomu T

PLoS genetics 20141009 10

Temperate phages infect bacteria by injecting their DNA into bacterial cells, where it becomes incorporated into the host genome as a prophage. In the genome of Bacillus subtilis 168, an active prophage, SPβ, is inserted into a polysaccharide synthesis gene, spsM. Here, we show that a rearrangement occurs during sporulation to reconstitute a functional composite spsM gene by precise excision of SPβ from the chromosome. SPβ excision requires a putative site-specific recombinase, SprA, and an acce ...[more]

PMID: 25299644

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Project description:The exosporium of Bacillus megaterium QM B1551 spores is morphologically distinct from exosporia observed for the spores of many other species. Previous work has demonstrated that unidentified genes carried on one of the large indigenous plasmids are required for the assembly of the Bacillus megaterium exosporium. Here, we provide evidence that pBM600-encoded orthologues of the Bacillus subtilis CotW and CotX proteins, which form the crust layer in spores of that species, are structural components of the Bacillus megaterium QM B1551 spore exosporium. The introduction of plasmid-borne cotW and orthologous cotX genes to the PV361 strain, which lacks all indigenous plasmids and produces spores that are devoid of an exosporium, results in the development of spores with a rudimentary exosporium-type structure. Additionally, purified recombinant CotW protein is shown to assemble at the air-water interface to form thin sheets of material, which is consistent with the idea that this protein may form a basal layer in the Bacillus megaterium QM B1551 exosporium.IMPORTANCE When starved of nutrients, some bacterial species develop metabolically dormant spores that can persist in a viable state in the environment for several years. The outermost layers of spores are of particular interest since (i) these represent the primary site for interaction with the environment and (ii) the protein constituents may have biotechnological applications. The outermost layer, or exosporium, in Bacillus megaterium QM B1551 spores is of interest, as it is morphologically distinct from the exosporia of spores of the pathogenic Bacillus cereus family. In this work, we provide evidence that structurally important protein constituents of the Bacillus megaterium exosporium are different from those in the Bacillus cereus family. We also show that one of these proteins, when purified, can assemble to form sheets of exosporium-like material. This is significant, as it indicates that spore-forming bacteria employ different proteins and mechanisms of assembly to construct their external layers.

Dataset Information

Developmentally-regulated excision of the SP? prophage reconstitutes a gene required for spore envelope maturation in Bacillus subtilis.

Publications

Developmentally-regulated excision of the SPβ prophage reconstitutes a gene required for spore envelope maturation in Bacillus subtilis.

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