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Description
Shiga toxin (Stx) prophages lysogenize various bacterial species, converting them into dangerous pathogens and driving the ongoing emergence of outbreaks. These pathogens are often polylysogens, harboring multiple prophages within their genomes. Yet, the impact of Stx prophage acquisition on resident prophages remains largely unknown. We show that upon infection the Stx prophage lysogenizes commensal Escherichia coli within the intestine. Markedly, this lysogenization altered the induction of resident prophages encoded within each new host strain. Moreover, Stx prophage lysogenization abolished the induction of φNP, the most active prophage of Citrobacter rodentium. We further show that φNP inhibition is mediated by the Stx Cro repressor, which exhibits dual-functionality, promoting its own lytic cycle while repressing the expression of φNP lytic genes. Our findings reveal a novel competition strategy among prophages, and suggest that interfering with the induction of co-hosted prophages plays a role in the emergence and evolution of new Stx-producing pathogens.
This work has been deposited on bioRxiv and is currently under peer review at Nature Communications.
