1. Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University , Newcastle Upon Tyne NE2 4AX, UK
2. Research Unit in Biology of Microorganisms, Department of Biology , Université de Namur, Namur, Belgium
3. Biodiscovery Institute, School of Chemistry, University of Nottingham , Nottingham NG7 2RD, UK
4. Blizard Institute, School of Biological and Behavioural Sciences, Queen Mary University of London , Newark street, London E1 2AT, UK