A tiny viral RNA can decisively tip the balance between life and death in infected bacteria.
In a study published in Molecular Cell, researchers report that bacteriophage lambda uses a short regulatory RNA—named PreS—to hijack its host’s DNA replication machinery. Rather than relying only on viral proteins, the phage deploys this small RNA to reprogram E. coli from the inside.
PreS binds to the bacterial messenger RNA of dnaN, a gene that encodes the β sliding clamp, an essential component of DNA replication. By reshaping the mRNA’s structure, the viral RNA boosts production of the clamp, effectively supplying the virus with more of the tools it needs to rapidly copy its own genome.
When PreS is removed or its binding site disrupted, viral replication slows and the destructive, lytic phase of infection is delayed. The finding reveals an unexpected layer of viral control and suggests that small RNAs may be common — and powerful — weapons in phage infections.
Beyond basic biology, the work could inform future phage therapy strategies, where understanding and tuning viral replication is key to turning bacteria’s natural predators into reliable medical tools.
