Salary for this Role: From £47,500 per annum plus benefits, subject to skills and experience Job Title: Postdoctoral Fellow Reports to: Simon Boulton Closing Date: 27/Oct/2026 23.59 GMT Job Description: Job title: Postdoctoral Fellow – S Boulton lab Reporting to: Simon J. Boulton, Principal Group Leader Contract term: This is a full-time, fixed term (4 year) position on Crick terms and conditions of employment. The Research Group Our research is focused on understanding the mechanisms that preserve genome stability, with emphasis on DNA double strand break (DSB) repair, the response to replication stress and the maintenance and protection of telomeres. Our work exploits a combination of genetics, functional genomics, proteomics, biochemistry and single molecule biophysics, which has allowed us to discover novel DNA repair genes and provide molecular insights into human diseases, including cancer, and disorders caused by telomere or replisome dysfunction. Most notably, our work has played an instrumental role in shaping our understanding of the regulation and execution of homologous recombination (HR), a key DSB repair pathway frequently inactivated in cancer, how the ends of chromosomes (telomeres) are protected from mis-repair, and more recently how cells sense and tolerate replication stress. This post is funded by a Wellcome Discovery Award to investigate the function and regulation of SLFN11 in replication stress tolerance, cancer development and therapy resistance. Project summary The tRNA nuclease SLFN11 is epigenetically silenced in approximately half of all treatment-naive tumours and is the single strongest predictor of resistance to DNA damaging chemotherapy. In response to replication stress, SLFN11 is activated and cleaves type II Leu-tRNAs, triggering translation shutdown and p53-independent apoptosis. We have recently established that SLFN11 is activated by unprotected single-stranded DNA following RPA exhaustion (Stanage et al. Nature Cell Biology 2025), identified NSUN2 and FAM122A as co-factors required with SLFN11 to eliminate cells experiencing heightened replication stress, uncovered a non-canonical function of SLFN11 and NSUN2 at the replication fork that is independent of tRNA cleavage and translation shutdown, and implicated loss of SLFN11 as a determinant of survival through telomere crisis and the establishment of alternative lengthening of telomeres (Segura-Bayona et al. Cell, In press). How SLFN11 is recruited to sites of replication stress, how it is restrained during normal DNA replication, and which factors positively and negatively regulate its activation, remain unresolved. The aim of this project is to define the regulatory architecture of the SLFN11 pathway using unbiased functional genomics. The post will conduct arrayed genome-wide CRISPR screens to identify positive and negative effectors of SLFN11 activation, exploiting a GFP-based reporter established in the lab in which every leucine residue of GFP is encoded by the TTA codon corresponding to the type II Leu-tRNA specifically cleaved by SLFN11, such that loss of GFP signal reports directly on SLFN11 nuclease activation. Complementary high-content imaging screens using endogenously tagged SLFN11 (Flag or ALFA) will be used to identify factors required for the recruitment of SLFN11 to sites of replication stress and for its subsequent re-localisation prior to tRNA cleavage. Screens will be performed under conditions that trigger the canonical and non-canonical arms of the pathway (DNA polymerase alpha inhibition and PARP inhibition, respectively) and will be conducted in collaboration with the High Throughput Screening STP at the Crick. Validated hits will be characterised in knockout and knock-in cell lines, and integrated with proteomic analysis of SLFN11 interactors and post-translational modifications generated in the lab. The project offers considerable scope to develop the mechanistic follow-up of hits, including cell biological, biochemical and single molecule approaches available in the lab. In this project, some of the specific aims could include but not be limited to: · Establishing and executing arrayed genome-wide CRISPR screens using the SLFN11-dependent GFP (TTA codon) reporter · Identifying factors required for SLFN11 recruitment to, and re-localisation from, sites of replication stress by high-content imaging · Validating and characterising positive and negative regulators of SLFN11 in gene-edited cell lines · Integrating screen hits with proteomic and post-translational modification datasets to define how SLFN11 activation is controlled Postdoctoral Fellows are expected to lead their own projects, contribute to other projects on a collaborative basis (both in the lab and with external collaborators) and guide PhD students in their research. The ability to work in a team is essential. Key experience and competencies The post holder should embody and demonstrate our core Crick values: bold, open, collegial, in addition to the following: Essential • PhD in molecular/cell biology, genome stability or a related discipline, or in the final stages of PhD submission • Good knowledge and experience in the study of genome stability, the DNA damage response and/or replication stress • Technical expertise in mammalian cell culture and genome engineering (CRISPR/Cas9, lentiviral and recombinase-based systems) • Experience of quantitative, image-based assays (immunofluorescence, confocal and/or high-content microscopy) and flow cytometry • Track record of writing papers as evidenced by publications or submitted manuscripts in referred journals • Evidence of data presentation at scientific meetings • Experience of experimental design, including the use of appropriate controls in large-scale experiments • Ability to work independently and also capable of interacting within a group Desirable • Experience of arrayed or pooled CRISPR screening and of the analysis of screen data • Familiarity with scrip