Work

Atypical Replication Error Pattern and Limited Repair Efficiency Contribute to Elevated Mutation Rate in Phage lambda

Year: 2025

Type: preprint

Abstract: Understanding the rate and nature of spontaneous mutations is crucial for understanding and modulating the pace and trajectory of evolution. Yet, both remain poorly characterized in double-stranded DNA (dsDNA) phages, despite their relevance for phage-based therapies. Here, we address this gap for the dsDNA phage lambda, using four complementary approaches: mutation accumulation assay combined with whole-genome sequencing, mutation visualization assay, duplex sequencing and fluctuation assay. We find that the mutation rate of wild-type phage lambda is 4.9 ± 1.8 x10 -9 per base per replication, approximately 15 times lower than previously estimated and about 20 times higher than that of its host, Escherichia coli ( E. coli ). Inactivation of Mismatch Repair (MMR), a major conserved cellular system for mutation avoidance, increases the lambda mutation rate by only 2-to 10-fold, in contrast to the approximately 150-fold increase in E. coli , however lambda does not exhibit the characteristic mutational bias associated with MMR deficiency. Interestingly replication of the lambda genome generates an error spectrum distinct from that of E. coli , characterized by a marked increase in transversions, poorly repaired by MMR. Together, these results reveal that lambda exhibits a replication error profile that is less amenable to repair, likely contributing to its elevated mutation rate.

Source: bioRxiv (Cold Spring Harbor Laboratory)

DOI: 10.1101/2025.08.29.673000