1. Department of Microbiology, Tumor and Cell Biology; Karolinska Institutet; Stockholm 171 77 Sweden
2. Department of Medical Biochemistry and Biophysics; Karolinska Institutet; Stockholm 171 77 Sweden
3. Department of Biological Sciences; Korea Advanced Institute of Science and Technology; Daejeon 305-701 Korea
4. The Helmholtz Center for Infection Research; Braunschweig 38124 Germany
5. Institute for Biophysical Chemistry; Hannover Medical School; Hannover 30625 Germany