title: Characterization of the Shigella and Salmonella Type III Secretion System Tip-Translocon Protein-Protein Interaction by Paramagnetic Relaxation Enhancement.
abstract: Many Gram-negative pathogens, such as Shigella and Salmonella, assemble the type III secretion system (T3SS) to inject virulence proteins directly into eukaryotic cells to initiate infectious diseases. The needle apparatus of the T3SS consists of a base, an extracellular needle, a tip protein complex, and a translocon. The atomic structure of the assembled tip complex and the translocon is unknown. Here, we show by NMR paramagnetic relaxation enhancement (PRE) that the mixed α-β domain at the distal region of the Shigella and Salmonella tip proteins interacts with the N-terminal ectodomain of their major translocon proteins. Our results reveal the binding surfaces involved in the tip-translocon protein-protein interaction and provide insights about the assembly of the needle apparatus of the T3SS.
authors.affiliation: Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66045, USA.
authors.forename: Kawaljit
authors.initials: K
authors.lastname: Kaur
authors.affiliation: Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66045, USA.
authors.forename: Srirupa
authors.initials: S
authors.lastname: Chatterjee
authors.affiliation: Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66045, USA.
authors.forename: Roberto N
authors.initials: RN
authors.lastname: De Guzman
mesh_terms: D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D011485:Protein Binding; D012475:Salmonella / Q000737:chemistry*; D012760:Shigella / Q000737:chemistry*; D000069296:Type III Secretion Systems / Q000737:chemistry* / Q000302:isolation & purification
chemical_list: D000069296:Type III Secretion Systems
keywords: SipB; SipD; paramagnetic relaxation enhancement; protein-protein interaction; type III secretion system