Identifying components of the Shewanella phage LambdaSo lysis system.

Lysis of bacteria can have multiple consequences, such as the release of host DNA to foster robust biofilm. Phage-induced lysis of Gram-negative cells requires the disruption of three layers, the outer and inner membranes and the cell wall. In most cases, the lysis systems of phages infecting Gram-negative cells comprise holins to disrupt or depolarize the membrane, thereby releasing or activating endolysins, which then degrade the cell wall. This, in turn, allows the spanins to become active and fuse outer and inner membranes, completing cell envelope disruption and allowing phage egress. Here, we show that the presence of these three components may not be sufficient to allow cell lysis, implicating that also in known phages, further factors may be required.