title: A repeat unit of Vibrio diarrheal T3S effector subverts cytoskeletal actin homeostasis via binding to interstrand region of actin filaments.
abstract: A novel bacterial type III secretion effector, VopV, from the enteric pathogen Vibrio parahaemolyticus has been identified as a key factor in pathogenicity due to its interaction with cytoskeletal actin. One of the repeat units in the long repetitive region of VopV, named VopV(rep1), functions as an actin-binding module. Despite its importance in pathogenesis, the manner in which the effector binds to actin and the subsequent effects on actin dynamics remain unclear. Here, we report the molecular basis of the VopV(rep1)/actin interaction. VopV(rep1) exists as an unstructured protein in solution but potently and specifically binds filamentous actin (F-actin) and not globular actin (G-actin). The F-actin/VopV(rep1) complex was directly visualized at 9.6-Å resolution using electron cryomicroscopy (cryoEM) and helical image reconstitution. The density map revealed the binding site of VopV(rep1) at the interface between two actin strands, which is close to the binding site of the bicyclic heptapeptide toxin phalloidin. Consistent with this observation, VopV(rep1) alone prevented the depolymerization of F-actin. Overall, VopVr(ep1) demonstrated unique characteristics in comparison to known actin-binding proteins, but was relatively similar to phalloidin. The phalloidin-like behavior, targeting the interstrand region of actin filaments to stabilize the filament structure, likely contributes to the pathogenicity of V. parahaemolyticus.
authors.affiliation: 1] Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan [2] Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka, 569-1094, Japan.
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Nishimura
authors.affiliation: 1] Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan [2] Riken Quantitative Biology Center, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Fujii
authors.affiliation: Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Hiyoshi
authors.affiliation: Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Fumiaki
authors.initials: F
authors.lastname: Makino
authors.affiliation: Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka, 569-1094, Japan.
authors.forename: Hajime
authors.initials: H
authors.lastname: Inoue
authors.affiliation: 1] Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan [2] Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka Suita, Osaka 565-0871, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Motooka
authors.affiliation: Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Toshio
authors.initials: T
authors.lastname: Kodama
authors.affiliation: Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka Suita, Osaka 565-0871, Japan.
authors.forename: Tadayasu
authors.initials: T
authors.lastname: Ohkubo
authors.affiliation: Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka, 569-1094, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kobayashi
authors.affiliation: Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Shota
authors.initials: S
authors.lastname: Nakamura
authors.affiliation: 1] Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan [2] Riken Quantitative Biology Center, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Namba
authors.affiliation: Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Iida
mesh_terms: D008841:Actin Cytoskeleton / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism; D002771:Cholera / Q000382:microbiology*; D003599:Cytoskeleton / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006706:Homeostasis; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation; D055503:Protein Multimerization; D055550:Protein Stability; D000069296:Type III Secretion Systems / Q000378:metabolism*; D014733:Vibrio / Q000502:physiology*
chemical_list: D001426:Bacterial Proteins; D000069296:Type III Secretion Systems