[1] Centre for Infectious Diseases, Wolfson Research Institute, University of Durham, Stockton-on-Tees, TS17 6BH, United Kingdom
[2] Division of Infection and Immunity, University of Glasgow, Glasgow G11 6NU, United Kingdom
[3] Div. of Biochem./Molecular Biology, Inst. of Biomed. and Life Sciences, University of Glasgow, Glasgow G11 6NU, United Kingdom
[4] Department of Chemistry, University of Glasgow, Glasgow G11 6NU, United Kingdom
[5] Natl. Ctr. for Macromolec. Hydrodyn., School of Biosciences, University of Nottingham, Sutton Bonington LE12 5RD, United Kingdom