PhD Studentship: Regulation of antimicrobial activity by phagosomal phosphoinositides
The capture and killing of invasive microorganisms by phagocytic immune cells is critical for the body’s defence against pathogens. It is therefore essential for professional phagocytes such as macrophages and neutrophils to rapidly and efficiently kill their prey to prevent the establishment of infections and disease. Multiple mechanisms are used to achieve this with phagosomes quickly becoming acidified and acquiring reactive oxygen species, antimicrobial peptides and acid hydrolases following engulfment. The timely and regulated delivery of these components is vital to protect the host from intracellular pathogens, but is still incompletely understood.
Phosphoinositide lipids (PIPs) are key regulators of vesicular trafficking. The interconversion of PIP species and subsequent recruitment of specific effectors provides a powerful mechanism to regulate membrane dynamics and is critical during phagosome maturation. Of the PIPs, PI(3,5)P2 is one of the least well understood due to its low abundance and the lack of reliable reporters. We have recently found that blocking PI(3,5)P2 synthesis by disrupting the PI5-kinase PIKfyve dramatically reduces proteolysis and killing of phagocytosed bacteria, allowing the pathogen Legionella pneumophila to survive and grow unrestrained.
Mechanistically however, the role of PI(3,5)P2 during phagosome maturation and killing remains unclear. The aims of this project are therefore to:
- Understand the dynamics and roles of PI(3,5)P2 during phagosome maturation and bacterial killing.
- Determine the mechanisms regulating phagosome maturation in response to bacteria
This project will use the amoeba Dictyostelium discoideum as a model system. Like immune cells, Dictyostelium are professional phagocytes but hunt and kill bacteria for food. Phagocytosis is highly conserved and this system allows us to combine genetic manipulation and high-resolution live imaging not possible with immune cells. We are then able to directly translate our work to a number of infectious diseases.
This studentship will provide training in a wide range of techniques including live super-resolution light microscopy, proteomics, biochemistry and molecular biology.
We are therefore seeking a talented and enthusiastic individual with interests in infectious disease and cell biology. Please see our website (http://king.group.shef.ac.uk) or contact directly for more information.
Science Graduate School
As a PhD student in one of the science departments at the University of Sheffield, you’ll be part of the Science Graduate School. You’ll get access to training opportunities designed to support your career development by helping you gain professional skills that are essential in all areas of science. You’ll be able to learn how to recognise good research and research behaviour, improve your communication abilities and experience the breadth of technologies that are used in academia, industry and many related careers. Visit http://www.sheffield.ac.uk/sgs to learn more.
King lab website: http://king.group.shef.ac.uk
- Buckley CM et al. WASH drives early recycling from macropinosomes and phagosomes to maintain surface phagocytic receptors. PNAS. 2016 Oct 4;113(40):E5906-E5915 http://www.pnas.org/content/113/40/E5906.short
- Gerstenmaier L et al. The autophagic machinery ensures nonlytic transmission of mycobacteria. PNAS. 2015. 112 (7), E687-E692 http://www.pnas.org/content/112/7/E687.short
- King JS et al. WASH is required for lysosomal recycling and efficient autophagic and phagocytic degradation. Mol. Biol. Cell. 2013. 24 (17), 2714-2726 http://www.molbiolcell.org/content/24/17/2714.short