Supervisors: Prof Paul Birch and Dr Piers Hemsley, Division of Plant Sciences and Prof Terry Smith, Biomedical Sciences Research Complex, University of St Andrews.
Plants must respond to pathogen insult in situ; as a result, plants have evolved a diverse range of biochemical processes to detect and destroy pathogens. The intra and extra-cellular receptors involved in this process are regulated by a range of post-translational modifications (e.g. Hurst et al., 2019 Scientific Reports 9:12818). We recently discovered that S-acylation, a fatty acid-based post-translational modification, affects plant perception of pathogens through these receptors. Unfortunately, our ability to study S-acylation in the context of plants is limited by technological barriers. This project aims to produce enabling tools to study how S-acylation regulates plant perception of pathogens.
Plants, being photoautotrophs, synthesise virtually all of the complex biological compounds needed for their existence. Coupled with their ease of genetic modification this makes them particularly attractive as bioreactors for clean production of novel and high value chemicals. Plant fatty acids and lipids are important factors in human health through our diets, but at a more fundamental level are essential for plant cellular homeostasis (membranes), tissue integrity (cuticular waxes), energy storage (seed oils) and protein regulation (S-acylation, N-myristoylation, etc.). Current methods to analyse plant fatty acid metabolism, partitioning and destination use radioactive tracers necessitating complex experimental set ups and limiting growth conditions that can be investigated. We would like to generate plants capable of endogenously producing non-natural fatty acids that can be tracked through their cellular metabolism, greatly improving the speed and physiological scope of analysis. Recently discovered proteins from some bacterial species are able to introduce terminal alkyne groups to fatty acids (Zhu et al., (2015) ACS Chem Biol. 10(12):2785-93). This project aims to make transgenic plants expressing these proteins to determine whether it is possible to manipulate plants to produce terminal alkynyl fatty acids that can act as substrates for azide-alkyne click chemistry tracking. The utility of these plants will be tested by examining the incorporation of endogenously produced alkynyl fatty acids into the S-acyl proteome and lipidome of the plants. We will then examine how the S-acylation state of individual plant pathogen receptors, and the wider proteome, changes in response to pathogen insult. This will allow us to define and investigate new regulatory mechanisms and proteins underlying plant survival in the face of pathogens. As a complementary approach, we will also test uptake of exogenous fatty acids into plants using a variety of novel chemically synthesised delivery vehicles (collaboration with Prof Nick Tomkinson, Strathclyde). Combined, these approaches will reveal how plants metabolise fatty acids, provide proof-of-concept for biological routes to novel natural products and deliver valuable experimental tools for the fatty acid and lipid research communities.
This project is multi-disciplinary, spanning plant biology, pathology, biotechnology and chemistry, and will involve training in molecular biology, chemical biology, protein biochemistry, mass spectrometry-based lipid analysis, click chemistry, chemical synthesis and plant transformation technology.