Revisited gene regulation in bacteriophage λ

The contribution of bacteriophage λ to gene control research is far from over. A revised model of the λ genetic switch includes extra cooperativity through octamerization of the cI repressor protein, mediated by long-range DNA looping. Structural analysis reveals remarkably subtle transcriptional activation by cI. The action of cI, activation by cII, and aspects of antitermination by N and Q all confirm the utility and versatility of simple, weak adhesive interactions mediated by nucleic acid tethers. New genetic and quantitative analysis of the λ gene network is challenging cherished ideas about how complex behaviours emerge from this regulatory system.