1. NCCR Chemical Biology and Department of Biochemistry, University of Geneva, 1211 Geneva, Switzerland
2. Department of Biochemistry, University of Oxford, OX1 3QU Oxford, United Kingdom
3. Department of Molecular Genetics, Weizmann Institute of Science, 76100 Rehovot, Israel
4. Department of Biomolecular Sciences, Weizmann Institute of Science, 76100 Rehovot, Israel