Abstract Coxiella burnetii is the causative agent of Q-fever, a zoonotic disease endemic globally and particularly in the South-West in the UK. C. burnetii is an obligate pathogen of ruminants: in livestock it causes abortions and still-births, with obvious economic consequences. C. burnetii is an opportunistic pathogen of humans with a very low infectious dose. Q-fever causes serious flu-like symptoms. Whilst these are usually self-resolving, some patients require hospital treatment, and some of these go on to suffer serious complications (e.g. myocarditis). C. burnetii is one of the causative agents of the so-called "desert fever" suffered by UK service personal in the Middle East, and has been associated with chronic fatigue syndrome. There is a clear need for effective treatments for C. burnetii. We are part of an ongoing (BBSRC funded) programme to produce a vaccine using the polysaccharide O-antigen of C. burnetii, the best current vaccine candidate. This O-antigen contains two highly unusual sugars (virenose and dihydrohydroxystreptose). We have identified several of the biosynthetic proteins that support our hypotheses on the biosynthesis. These enzymes display at least two novel enzyme activities, which may provide excellent opportunities to make specific inhibitors. We have protocols to prepare proteins in high quantities, which should be sufficient to determine the protein structures. The main supervisor will collaborate with Diamond Light Source to use the upcoming micro-electron diffraction method as part of this structure solution. In this project, the student will select the most scientifically interesting proteins from the biosynthetic pathway. The student will determine the structure of these proteins, and will test the wild-type enzyme and selected mutants for enzyme activity. The student will test the activity of the enzymes in recombinant E. coli pathways to confirm the effects of mutants. The student will particularly look for enzyme variants that display altered activity that might be valuable in the whole-cell context. The student will also work with modelling software to study the enzymes using molecular dynamics and quantum mechanical simulations to support proposed enzymatic mechanisms. These data will then be used to model drug binding to the proteins as a first step towards drug development. The student's work will demonstrate the mechanisms of the novel enzymes in the O-antigen pathway. The student's work will also contribute to the development of recombinant O-antigen for vaccine development and the first stages of drug discovery. This work will therefore have both academic and practical outputs. https://gtr.ukri.org/projects?ref=studentship-2579050
