A model for the Escherichia coli FtsB/FtsL/FtsQ cell division complex

Two oligomeric models for the periplasmic region of the FtsB/FtsL/FtsQ E. coli complex were obtained from bioinformatics analysis. The FtsB/FtsL subcomplex was modelled as a coiled-coil based on sequence information and several stoichiometric possibilities. The crystallographic structure of FtsQ was added to this complex, through protein-protein docking. Two final structurally-stable models, one trimeric and one hexameric, were obtained. The nature of the protein-protein contacts was energetically favourable in both models and the overall structures were in agreement with the experimental evidence reported.The two models obtained for the FtsB/FtsL/FtsQ complex were stable and thus compatible with the in vivo periplasmic complex structure. Although the hexameric model 2:2:2 has features that indicate that this is the most plausible structure, the ternary complex 1:1:1 cannot be discarded. Both models could be further stabilized by the binding of the other proteins of the divisome. The bioinformatics modelling of this kind of protein complex, whose function is mainly structural, provide useful information. Experimental results should confirm or reject these models and provide new data for future bioinformatics studies to refine the models.Bacterial cell division is performed at the middle of the cell, after duplication and segregation of the genetic material into the daughter nucleoids. In Escherichia coli, this process requires at least 12 essential proteins, localized at the constriction site at the cell equator. These proteins coordinate the invagination of the cytoplasmic membrane and guide the inward growth of the peptidoglycan to produce the daughter cells. The proteins FtsZ, FtsA, ZipA, FtsE/FtsX, FtsK, FtsQ, FtsB/FtsL, FtsW, FtsI and FtsN have been identified mainly through microscopy observation of GFP-protein fusions and deletions of the corresponding gene (reviewed in [1] and [2]).The E. coli divisome, the macromolecular complex composed of the aforemention