1. Institute of Molecular Biology and Pathology, CNR National Research Council, c/o Department of Biology and Biotechnology, Sapienza Università di Roma, Roma, Italy
2. Present address: IRBM Science Park, Advent Srl, Pomezia, Italy
3. Present address: EMBL, Heidelberg, Germany
4. Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Department of Drug Chemistry and Technology, Sapienza Università di Roma, Roma, Italy