A growth-inhibitory dUTPase from Mosigvirus AV110 disrupts cell division and host physiology in Escherichia coli

dUTPases are essential enzymes for nucleotide metabolism as they catalyze the hydrolysis of dUTP to dUMP, thus preventing the toxic incorporation of uracil into DNA. dUTPases are found in all domains of life, including bacteriophages, where they serve multiple functions to support phage propagation. Phage-encoded dUTPases reduce cellular dUTP levels and provide precursors for de novo dTTP synthesis and the synthesis of modified nucleotides, which are important to avoid DNA-based phage defense systems. In this study, we focused on the dimeric dUTPase Gp135, encoded by the Mosigvirus phage AV110, and examined its effect on growth, cell morphology, DNA replication and cell division of AV110s host, extended-spectrum beta-lactamase-producing E. coli. We observed that Gp135 significantly inhibited growth by disrupting DNA replication and cell division. This resulted in cytoplasmic voids, cell elongation, and ultimately cell death. We further demonstrated the diversity of phage-encoded dUTP/dCTPases through phylogenetic analysis, identifying four distinct clusters: one comprising the most common dUTPases, which form trimers; two more divergent clusters comprising dimeric dUTP/dCTPases; and one new cluster of more diverse, uncharacterized dUTPases and dNTPases. Overall, our results highlight the evolutionary and functional diversity of phage-encoded dUTP/dCTPases, with the Mosigvirus AV110 dUTP/dCTPase illustrating their role in supporting phage propagation.