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bioRxiv · 10.1101/2020.07.13.199331

Prophage-encoded phage defence proteins with cognate self-immunity

Owen, S. V.·Wenner, N.·Dulberger, C. L.·Rodwell, E. V.·Bowers-Barnard, A.·Quinones-Olvera, N.·Rigden, D. J.·Rubin, E. J.·Garner, E. C.·Baym, M.·Hinton, J. C. D.
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Abstract

Temperate phages are pervasive in bacterial genomes, existing as vertically-inherited islands called prophages. Prophages are vulnerable to the predation of their host bacterium by exogenous phages. Here we identify BstA, a novel family of prophage-encoded phage defense proteins found in diverse Gram-negative bacteria. BstA drives potent suppression of phage epidemics through abortive infection. During lytic replication, the bstA-encoding prophage is not itself inhibited by BstA due to a self-immunity mechanism conferred by the anti-BstA (aba) element, a short stretch of DNA within the bstA locus. Inhibition of phage replication by distinct BstA proteins from Salmonella, Klebsiella and Escherichia prophages is functionally interchangeable, but each possesses a cognate aba element. The specificity of the aba element ensures that immunity is exclusive to the replicating prophage, and cannot be exploited by heterologous BstA-encoding phages. BstA allows prophages to defend host cells against exogenous phage attack, without sacrificing their own lytic autonomy.

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Owen, S. V., Wenner, N., Dulberger, C. L., Rodwell, E. V., Bowers-Barnard, A., Quinones-Olvera, N., Rigden, D. J., Rubin, E. J., Garner, E. C., Baym, M., Hinton, J. C. D.. 2020-07-13. Prophage-encoded phage defence proteins with cognate self-immunity. https://doi.org/10.1101/2020.07.13.199331

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