Genomic and functional divergence analysis of closely related Teseptimavirus phages reveals dual HNH endonuclease positioning and its role in plaque formation.

Dual positioning of HNH endonuclease in Teseptimavirus phages influences plaque formation and infection traits, with a single nucleotide change significantly enhancing phage infectivity.

• Why it matters: Understanding the genetic factors behind phenotypic diversity in closely related phages is crucial for optimizing their use in therapy and biocontrol, especially amid rising antibiotic resistance.
• What they did: Comparing two T7-like phages, C5 and N30, researchers performed genomic analyses and structural predictions, revealing two distinct HNH endonuclease positions and their association with infection phenotypes, including a key single nucleotide substitution.
• The result: Findings demonstrate that the HNH endonuclease's genomic location and sequence variation are pivotal in determining plaque formation efficiency, offering new avenues for phage engineering and understanding host adaptation.