[1] Univ Kaiserslautern, Dept Microbiol, D-67663 Kaiserslautern, Germany
[2] CSIC UAM, Ctr Biol Mol Severo Ochoa, Madrid 28049, Spain
[3] Free Univ Berlin, Dahlem Ctr Plant Sci, D-14195 Berlin, Germany
[4] Newcastle Univ, Inst Cell & Mol Biosci, Ctr Bacterial Cell Biol, Newcastle Upon Tyne NE2 4AX, Tyne & Wear, England