About the Authors
International Centre for Genetic Engineering and Biotechnology, Trieste, Italy
Division of Molecular Biosciences, Faculty of Natural Sciences, Imperial College London, London, United Kingdom
The authors have declared that no competing interests exist.
LM, FB, PSF, and AV conceived and designed the experiments. LM, FB, VP, SC, BN, and MR performed the experiments. AP and AV analyzed the data. AV wrote the paper.