1. The Centre for Food and Microbial Technology, Department of Microbial and Molecular Systems, Katholieke Universiteit Leuven, Kasteelpark Arenberg 22, B-3001 Heverlee, Belgium
2. Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, Katholieke Universiteit Leuven, Kasteelpark Arenberg 31, B-3001 Heverlee, Belgium
3. Department of Molecular Microbiology, VIB, Katholieke Universiteit Leuven, B-3001 Heverlee, Belgium
4. FAS Center for Systems Biology, Harvard University, 7 Divinity Avenue, Cambridge, Massachusetts 02138