1. Department Genetics of Microorganisms; Interfaculty Institute for Genetics and Functional Genomics; Ernst Moritz Arndt University of Greifswald; D-17487 Greifswald Germany
2. Department of Crystallography and Structural Biology; Institute of Physical-Chemistry ‘Rocasolano’; CSIC; Serrano 119 28006 Madrid Spain
3. Division of Bioanalytical Chemistry; Research Center Borstel, Leibniz-Center for Medicine and Biosciences; D-23845 Borstel Germany
4. Department of Molecular Infection Biology; Central Facility for Microscopy; Helmholtz Centre for Infection Research; D-38124 Braunschweig Germany