The integral membrane FtsW protein and peptidoglycan synthase PBP3 form a subcomplex in Escherichia coli.
During the cell cycle of rod-shaped bacteria, two morphogenetic processes can be discriminated: length growth of the cylindrical part of the cell and cell division by formation of two new cell poles. The morphogenetic protein complex responsible for the septation during cell division (the divisome) includes class A and class B penicillin-binding proteins (PBPs). In Escherichia coli, the class B PBP3 is specific for septal peptidoglycan synthesis. It requires the putative lipid II flippase FtsW for its localization at the division site and is necessary for the midcell localization of the class A PBP1B. In this work we show direct interactions between FtsW and PBP3 in vivo and in vitro by FRET (Förster resonance energy transfer) and co-immunoprecipitation experiments. These proteins are able to form a discrete complex independently of the other cell-division proteins. The K2-V42 peptide of PBP3 containing the membrane-spanning sequence is a structural determinant sufficient for interaction with FtsW and for PBP3 dimerization. By using a two-hybrid assay, the class A PBP1B was shown to interact with FtsW. However, it could not be detected in the immunoprecipitated FtsW-PBP3 complex. The periplasmic loop 9/10 of FtsW appeared to be involved in the interaction with both PBP1B and PBP3. It might play an important role in the positioning of these proteins within the divisome.
Fraipont
Claudine
C
Centre d'Ingénierie des Protéines, Université de Liège, Institut de Chimie, B6a, B-4000 Sart-Tilman, Belgium.
Alexeeva
Svetlana
S
Molecular Cytology, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 1098 XH Amsterdam, The Netherlands.
Wolf
Benoît
B
Centre d'Ingénierie des Protéines, Université de Liège, Institut de Chimie, B6a, B-4000 Sart-Tilman, Belgium.
van der Ploeg
René
R
Molecular Cytology, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 1098 XH Amsterdam, The Netherlands.
Schloesser
Marie
M
Centre d'Ingénierie des Protéines, Université de Liège, Institut de Chimie, B6a, B-4000 Sart-Tilman, Belgium.
den Blaauwen
Tanneke
T
Molecular Cytology, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 1098 XH Amsterdam, The Netherlands.
Nguyen-Distèche
Martine
M
Centre d'Ingénierie des Protéines, Université de Liège, Institut de Chimie, B6a, B-4000 Sart-Tilman, Belgium.
D001426:Bacterial Proteins / Q000378:metabolism*; D004926:Escherichia coli / Q000737:chemistry*; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods; D047468:Immunoprecipitation; D008565:Membrane Proteins / Q000378:metabolism*; D008958:Models, Molecular; D046915:Penicillin-Binding Proteins / Q000378:metabolism*; D054730:Protein Interaction Domains and Motifs; D025941:Protein Interaction Mapping; D055503:Protein Multimerization; D020798:Two-Hybrid System Techniques
D001426:Bacterial Proteins; D008565:Membrane Proteins; D046915:Penicillin-Binding Proteins; C061684:FtsW protein, Bacteria