Crystal Structure of an Outer Membrane-Anchored Endolytic Peptidoglycan Lytic Transglycosylase (MltE) from Escherichia coli

C476 domain (FlhBc). Homologues of FlhB were found in all bacterial type III secretion systems. The sequence of the protein is highly conserved suggesting that the protein function is also similar. We have investigated complementation properties of FlhB from Aquifex aeolicus to FlhB from Salmonella typhimurium. flhB gene in Salmonella was substituted by flhB of A. aeolicus or by chimera flhB composed of different parts from A. aeolicus flhB and S. typhimurium flhB. Such mutants were tested for motility. All mutants showed motility although weaker than wild cells. We have found that some mutations in C-terminal part of FlhB resulted in enhanced motility. To explain results obtained we have determined FlhBc structures from both organisms: S. typhimurium and A. aeolicus. Comparison of the structures gives us new ideas about functional mechanism of FlhB.