1. Department of Life and Environmental Sciences, University of Cagliari, Cagliari 09042, Italy
2. Department of Pharmacy, School of Medicine and Surgery, University of Naples Federico II, Naples 80131, Italy
3. The Max-Planck Institute of Biochemistry, Department of Molecular Structural Biology, Martinsried 82152, Germany
4. Istituto di Ricerca Genetica e Biomedica, Consiglio Nazionale delle Ricerche (CNR), Monserrato 09042, Italy