1. Department of Cell Biology, Yale School of Medicine, New Haven, CT 06511, USA. Tel.: ; E-mail: arunima.chaudhuri@yale.edu
2. Max-Planck-Institut für terrestrische Mikrobiologie, Karl-von-Frisch-Straße 10, D-35043 Marburg, Germany. Tel.: ; E-mail: deepak.anand@mpi-marburg.mpg.de