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Article
Weak Interactions between Salmonella enterica FlhB and Other Flagellar Export Apparatus Proteins Govern Type III Secretion Dynamics
Faculty Publications
  • Jonathan L. McMurry, Kennesaw State University
  • Tohru Minamino, Osaka University
  • Yukio Furukawa, Osaka University
  • Joshua W. Francis, Kennesaw State University
Department
Molecular & Cellular Biology
Document Type
Article
Publication Date
8-5-2015
Abstract
The bacterial flagellum contains its own type III secretion apparatus that coordinates protein export with assembly at the distal end. While many interactions among export apparatus proteins have been reported, few have been examined with respect to the differential affinities and dynamic relationships that must govern the mechanism of export. FlhB, an integral membrane protein, plays critical roles in both export and the substrate specificity switching that occurs upon hook completion. Reported herein is the quantitative characterization of interactions between the cytoplasmic domain of FlhB (FlhBC) and other export apparatus proteins including FliK, FlhAC and FliI. FliK and FlhAC bound with micromolar affinity. KD for FliI binding in the absence of ATP was 84 nM. ATP-induced oligomerization of FliI induced kinetic changes, stimulating fast-on, fast-off binding and lowering affinity. Full length FlhB purified under solubilizing, nondenaturing conditions formed a stable dimer via its transmembrane domain and stably bound FliH. Together, the present results support the previously hypothesized central role of FlhB and elucidate the dynamics of protein-protein interactions in type III secretion.
Digital Object Identifier (DOI)
10.1371/journal.pone.0134884
Citation Information
McMurry JL, Minamino T, Furukawa Y, Francis JW, Hill SA, Helms KA, et al. (2015) Weak Interactions between Salmonella enterica FlhB and Other Flagellar Export Apparatus Proteins Govern Type III Secretion Dynamics. PLoS ONE 10(8): e0134884. doi:10.1371/journal.pone.0134884