The role of small open reading frames in Shewanella oneidensis phage LambdaSo in host takeover and phage proliferation

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Phages are viruses that prey on bacteria. They are amazingly abundant in nature and affect the ecology of bacteria including all elemental cycles or the microbiome of humans. Generally, phage-host interaction occurs in two major fashions. In the lytic phage cycle, the phage attaches to its host and the phage chromosome is transported into the host cell. There, major cell functions are taken over and are redirected towards the production of novel phage particles, which are then released upon lysis -and death- of the host cell. In contrast, lysogenic phages are able to stably establish the chromosome as a prophage in the host cell, which will then propagate the phage genome during cell division. Upon certain signals, such as increased cell stress, the prophage is activated and its lytic cycle is triggered, leading to production of phage particles and their release by cell lysis. In billions of years of co-evolution, host and phages have evolved a huge amount of attack and defense mechanisms, most of which are still unknown, also due to the large number of uncharacterized phages. In this proposed project we are aiming at the in-depth characterization of small phage effector proteins that allow host-takeover and proliferation of the lysogen LambdaSo phage of Shewanella oneidensis. We will use a broad array of genetics, protein biochemistry and fluorescence microscopy to understand how two small proteins are able to take over cell growth and division of the host as well as to control the terminal cell lysis and phage release. We expect that the results will give fundamentally novel insights into the processes phages use to affect their host’s elementary functions.