1. Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom
2. DSM Biotechnology Center, P.O. Box 1, 2600 MA Delft, The Netherlands
3. Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands