Project Abstract: In most environments including the human host in the context of chronic infections, bacteria often face starvation and are not actively growing. Starved bacteria are intrinsically tolerant to conventional antibiotics that target activities important for growth but dispensable for starvation, such as DNA replication and cell wall biosynthesis. There is a pressing need, therefore, to understand activities that are important to bacteria for starvation survival. One widely conserved starvation response in bacteria is to globally remodel and compact the chromosome in order to silence transcription and protect the chromosome from damage due to environmental insults when resources may become limited. A key structural protein bacteria use to silence and protect DNA is called H-NS. H-NS can oligomerize on the chromosome to form large regions of silenced, compacted DNA, the bacterial functional analogue to eukaryotic chromatin. Bacteria also use H-NS to combat phage, by silencing phage DNA. Bacterial heterochromatin is therefore an important battleground in the arms race between phage and their bacterial hosts. The core strategy of this proposal is to exploit phage to learn about bacterial heterochromatin in the opportunistic human pathogen Pseudomonas aeruginosa. Understanding of how phage fights against heterochromatin silencing by its host has the potential to provide inspiration for novel antimicrobial therapies that target starved bacteria.