title: Profilin is required for sustaining efficient intra- and intercellular spreading of Shigella flexneri.
abstract: The ability of Shigella to mediate actin-based motility within the host cell is a prominent pathogenic feature of bacillary dysentery. The ability is dependent on the interaction of VirG with neural Wiskott-Aldrich syndrome protein (N-WASP), which in turn mediates recruitment of Arp2/3 complex and several actin-related proteins. In the present study, we show that profilin I is essential to the rapid movement of Shigella in epithelial cells, for which the capacity of profilin to interact with G-actin and N-WASP is critical. In COS-7 cells overexpressing either mutated profilin H119E, which failed to bind G-actin, or H133S, which is unable to interact with poly-l-proline, Shigella motility was significantly inhibited. Similarly, depletion of profilin from Xenopus egg extracts resulted in a decrease in bacterial motility that was completely rescued by adding back profilin I but not H119E or H133S. In COS-7 cells overexpressing a N-WASP mutant lacking the proline-rich domain (Deltap) unable to interact with profilin, the actin tail formation of intracellular Shigella was inhibited. In N-WASP-depleted extracts, addition of Deltap but not full-length N-WASP was unable to restore the bacterial motility. Furthermore, in a plaque formation assay with Madin-Darby canine kidney cell monolayers infected by Shigella, Madin-Darby canine kidney cells stably expressing H119E, H133S, or Deltap reduced the bacterial cell-to-cell spreading. These results indicate that profilin I associated with N-WASP is an essential host factor for sustaining efficient intra- and intercellular spreading of Shigella.
authors.affiliation: Division of Bacterial Infection, Department of Microbiology and Immunology, Department of Biochemistry, Institute of Medical Science, University of Tokyo, Minato-ku, Tokyo 108-8639, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Mimuro
authors.forename: T
authors.initials: T
authors.lastname: Suzuki
authors.forename: S
authors.initials: S
authors.lastname: Suetsugu
authors.forename: H
authors.initials: H
authors.lastname: Miki
authors.forename: T
authors.initials: T
authors.lastname: Takenawa
authors.forename: C
authors.initials: C
authors.lastname: Sasakawa
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D001426:Bacterial Proteins; D019556:COS Cells; D003285:Contractile Proteins; D004268:DNA-Binding Proteins / Q000502:physiology; D004285:Dogs; D008840:Microfilament Proteins / Q000502:physiology*; D009068:Movement; D009419:Nerve Tissue Proteins / Q000502:physiology; D051304:Profilins; D011817:Rabbits; D012763:Shigella flexneri / Q000502:physiology*; D014157:Transcription Factors / Q000502:physiology; D051317:Wiskott-Aldrich Syndrome Protein, Neuronal; D014981:Xenopus
chemical_list: D000199:Actins; D001426:Bacterial Proteins; D003285:Contractile Proteins; D004268:DNA-Binding Proteins; D008840:Microfilament Proteins; D009419:Nerve Tissue Proteins; D051304:Profilins; D014157:Transcription Factors; D051317:Wiskott-Aldrich Syndrome Protein, Neuronal; C058483:virG protein, Shigella flexneri