title: Roles of the TonB1 and TonB2 proteins in haemin iron acquisition and virulence in Riemerella anatipestifer.
abstract: Two TonB systems in Riemerella anatipestifer were found and characterized as ExbB1-ExbD1-TonB1 and ExbB2-ExbD2-ExbD2'-TonB2, but the significance of two sets of TonB complexes in R. anatipestifer is not clear. In this study, by deleting the tonB1 or tonB2 gene of R. anatipestifer strain CH3, we investigated the roles of the TonB1 and TonB2 proteins in iron acquisition and virulence. The results showed that strain CH3 could utilize haemin as the sole iron source in the presence of l-cysteine, but haemin iron acquisition was defective in the CH3ΔtonB1 mutant, and the deletion of either tonB1 or tonB2 significantly reduced adhesion to and invasion of Vero cells. Animal experiments indicated that the LD50 of the CH3ΔtonB1 and CH3ΔtonB2 mutants in ducklings was ∼224- and ∼87-fold, respectively, higher than that of the WT CH3 strain. Additional analysis indicated that blood bacterial loading of ducklings infected with CH3ΔtonB1 or CH3ΔtonB2 decreased significantly compared with that found for WT CH3-infected ducklings. Thus, our results indicated that the TonB1, but not TonB2 protein, is involved in haemin iron acquisition and that both TonB proteins are necessary for optimal bacterial virulence.
authors: Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, 518 Ziyue Road, Shanghai 200241, PR China.
authors: Shuang
authors: S
authors: Miao
authors: Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, 518 Ziyue Road, Shanghai 200241, PR China.
authors: Linlin
authors: L
authors: Xing
authors: Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, 518 Ziyue Road, Shanghai 200241, PR China.
authors: Jingjing
authors: J
authors: Qi
authors: Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, 518 Ziyue Road, Shanghai 200241, PR China.
authors: Hui
authors: H
authors: Yu
authors: Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, 518 Ziyue Road, Shanghai 200241, PR China.
authors: Pan
authors: P
authors: Jiang
authors: Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, 518 Ziyue Road, Shanghai 200241, PR China.
authors: Bingqing
authors: B
authors: Sun
authors: Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, 518 Ziyue Road, Shanghai 200241, PR China.
authors: Junsheng
authors: J
authors: Cui
authors: Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, 518 Ziyue Road, Shanghai 200241, PR China.
authors: Changcan
authors: C
authors: Ou
authors: Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, 518 Ziyue Road, Shanghai 200241, PR China.
authors: Qinghai
authors: Q
authors: Hu
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D002522:Chlorocebus aethiops; D004372:Ducks; D045826:Flavobacteriaceae Infections / Q000382:microbiology / Q000662:veterinary*; D006427:Hemin / Q000378:metabolism*; D007501:Iron / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D011201:Poultry Diseases / Q000382:microbiology*; D060494:Riemerella / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity*; D014709:Vero Cells; D014774:Virulence
chemical_list: D001426:Bacterial Proteins; D008565:Membrane Proteins; C057616:tonB protein, Bacteria; D006427:Hemin; D007501:Iron