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Question: Tyrosine phosphorylation of signalling proteins at the plasma membrane controls essential actin-dependent processes in eukaryotes, including migration, adhesion, and communication. Several pathogens mimic these signalling pathways to promote their own spread. The Basant lab uses the Vaccinia virus as a model system to understand phosphotyrosine signalling. While tyrosine kinases have been the subject of extensive research, their critical counterparts - tyrosine phosphatases - remain far less studied. How do phosphatases regulate these processes? The lab has previously identified tyrosine phosphatases that are involved in Vaccinia virus-directed actin dynamics. How do these molecules function?
Approach: This project will focus on the spatiotemporal regulation of the phosphatases PTPRA and PRL-2, both of which can bind membranes. Using CRISPR and RNAi-based approaches, we will replace these proteins in mammalian cell lines with truncated, mutant and fluorescently tagged variants and assay for localisation to the virus, cell membrane and the impact on actin dynamics. To identify interactors and substrates of PTPRA and PRL-2, we will use proximity-labelling and mass-spectrometry to identify host and viral, protein and lipidic interactors. Candidate interactions will be verified in cells by immunoprecipitation and co-labelling, and functionally tested in infected and uninfected cells.
Training: This project explores basic questions in cell signalling by combining cell biology, molecular biology and quantitative light microscopy methods with mass spectrometric approaches. The PhD candidate will be well-trained to think and apply these complementary lines of research to address a scientific problem.
Environment: The Basant lab is in the Randall Centre for Cell and Molecular Biophysics on the Guy’s Campus of King’s College London. The Randall has a positive and inclusive research culture, with many labs investigating exciting questions in cell biology, which will provide a rich and stimulating environment for the PhD candidate to train in.
Further reading: Vaccinia virus as a model to study signalling: The relative binding position of Nck and Grb2 adaptors impacts actin-based motility of Vaccinia virus (Basant A and Way M, eLife 2022 PMID: 35796545). Overview of the vast world of tyrosine phosphatases: Protein tyrosine phosphatases--from housekeeping enzymes to master regulators of signal transduction (Tonks NK, 2013, FEBS Letters PMID: 23176256)
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