Teh, M.Tran, N.Morona, R.2013-01-072013-01-072012Microbiology, 2012; 158(11):2835-28501350-08721465-2080http://hdl.handle.net/2440/74744The Shigella flexneri IcsA (VirG) protein is a polarly distributed autotransporter protein. IcsA functions as a virulence factor by interacting with the host actin regulatory protein N-WASP, which in turn activates the Arp2/3 complex, initiating actin polymerization. Formation of F-actin comet tails allows bacterial cell-to-cell spreading. Although various accessory proteins such as periplasmic chaperones and the β-barrel assembly machine (BAM) complex have been shown to be involved in the export of IcsA, the IcsA translocation mechanism remains to be fully elucidated. A putative autochaperone (AC) region (amino acids 634–735) located at the C-terminal end of the IcsA passenger domain, which forms part of the self-associating autotransporter (SAAT) domain, has been suggested to be required for IcsA biogenesis, as well as for N-WASP recruitment, based on mutagenesis studies. IcsAi proteins with linker insertion mutations within the AC region have a significant reduction in production and are defective in N-WASP recruitment when expressed in smooth LPS (S-LPS) S. flexneri. In this study, we have found that the LPS O antigen plays a role in IcsAi production based on the use of an rmlD (rfbD) mutant having rough LPS (R-LPS) and a novel assay in which O antigen is depleted using tunicamycin treatment and then regenerated. In addition, we have identified a new N-WASP binding/interaction site within the IcsA AC region.en© 2012 SGMHela CellsHumansShigella flexneriDysentery, BacillaryO AntigensBacterial ProteinsDNA-Binding ProteinsTranscription FactorsDown-RegulationAmino Acid MotifsProtein BindingProtein TransportMutationWiskott-Aldrich Syndrome Protein, NeuronalPromoter Regions, GeneticJournal article002012283410.1099/mic.0.062471-00003121792000162-s2.0-8486832352522682Tran, N. [0000-0003-1644-2287]Morona, R. [0000-0001-7009-7440]