Rep and UvrD are accessory helicases that promote movement of the DNA replication machinery through protein-DNA blocks. Understanding their function gives us important insights into the conflicts between replication and transcription. Escherichia coli that lack either rep or uvrD are viable, but the loss of both genes is lethal. This lethality can be reversed by compensatory suppressor mutations elsewhere in the bacterial genome. We have already generated one such suppressor strain and are looking for a student to identify this new mutation. We have used high throughput sequencing to compile a list of candidate suppressor genes and during this project the student will test each candidate mutation for suppression of the rep/uvrD lethality. The student will learn to work with E. coli, design and carry out PCR, make viral lysates, perform phage transductions, and carry out plasmid loss assays. This project would suit a student interested in microbiology and genetics. Identification of the suppressor mutation will be followed by analysis aiming to characterise the suppressive mechanism. Students will be expected to present their findings orally at a research day in York in September 2023.