H-NS silences antiviral immunity through 3D chromatin compaction
Bacterial antiviral immunity systems can be toxic to their hosts and must be tightly regulated. Immunity genes are often encoded by AT-rich mobile genetic elements subjected to silencing by nucleoid binding protein H-NS. Using RNA-seq, ChIP-seq, and chromosome 3D reconstruction with Micro-C, we find that H-NS binds and compacts bacterial immunity loci. H-NS deletion reveals anti-phage activity in…
Bacterial immune systems can be harmful to their hosts and require tight regulation. Genes for immunity are frequently found on mobile genetic elements called AT-rich elements, which are silenced by a protein called H-NS. Researchers used RNA sequencing, ChIP sequencing, and 3D chromosome reconstruction to examine this process. They discovered that H-NS binds to and compacts these immunity loci using three-dimensional structures.
Deleting H-NS in common Escherichia coli strains, which are typically vulnerable to phages, revealed enhanced anti-phage activity. Extending this method to environmental samples, the team found that getting rid of H-NS silencing boosted defense mechanisms, enabling bacteria to counter phages with anti-defense proteins. Additionally, the researchers found Madara, a new immunity system that works in tandem with the BREX defense.
The findings underscore H-NS as a crucial controller of bacterial immunity and emphasize the significance of expression levels for effective anti-phage activity in natural hosts.
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