Sporulation is a finely regulated morphogenetic program important in the ecology and epidemiology of
Clostridium botulinum. Exogenous elements disrupting sporulation-associated genes contribute to sporulation regulation and introduce diversity in the generally conserved sporulation programs of endospore formers. We identified a novel prophage-like
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Sporulation is a finely regulated morphogenetic program important in the ecology and epidemiology of
Clostridium botulinum. Exogenous elements disrupting sporulation-associated genes contribute to sporulation regulation and introduce diversity in the generally conserved sporulation programs of endospore formers. We identified a novel prophage-like DNA segment, termed the
yin element, inserted within
yabG, encoding a sporulation-specific cysteine protease, in an environmental isolate of
C. botulinum. Bioinformatic analysis revealed that the genetic structure of the
yin element resembles previously reported mobile intervening elements associated with sporulation genes. Within a pure
C. botulinum culture, we observed two subpopulations of cells with the
yin element either integrated into the
yabG locus or excised as a circular DNA molecule. The dynamics between the two observed conformations of the
yin element was growth-phase dependent and likely mediated by recombination events. The
yin element was not required for sporulation by
C. botulinum but triggered an earlier entry into sporulation than in a related isolate lacking this element. So far, the
yin element has not been found in any other
C. botulinum strains or other endospore-forming species. It remains to be demonstrated what kind of competitive edge it provides for
C. botulinum survival and persistence.
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