title: Pseudomonas fluorescens: iron-responsive proteins and their involvement in host infection.
abstract: For pathogenic bacteria, the ability to acquire iron is vital to survival in the host. In consequence, many genes involved in iron acquisition are associated with bacterial virulence. Pseudomonas fluorescens is a bacterial pathogen to a variety of farmed fish. However, the global regulatory function of iron in pathogenic P. fluorescens is essentially unknown. In this study, in order to identify proteins affected by iron condition at the expression level, we performed proteomic analysis to compare the global protein profiles of P. fluorescens strain TSS, a fish pathogen, cultured under iron-replete and iron-deplete conditions. Twenty-two differentially expressed proteins were identified, most of which were confirmed to be regulated by iron at the mRNA level. To investigate their potential involvement in virulence, the genes encoding four of the 22 proteins, i.e. HemO (heme oxygenase), PspB (serine protease), Sod (superoxide dismutase), and TfeR (TonB-dependent outermembrane ferric enterobactin receptor), were knocked out, and the pathogenicity of the mutants was examined in a model of turbot (Scophthalmus maximus). The results showed that compared to the wild type, the hemO, pspB, and tfeR knockouts were significantly impaired in the ability to survive in host serum, to invade host tissues, and to cause host mortality. Immunization of turbot with recombinant TfeR (rTfeR) and PspB induced production of specific serum antibodies and significant protections against lethal TSS challenge. Further analysis showed that rTfeR antibodies recognized and bound to TSS, and that treatment of TSS with rTfeR antibodies significantly impaired the infectivity of TSS to fish cells. Taken together, these results indicate for the first time that in pathogenic P. fluorescens, iron affects the expression of a large number of proteins including those that are involved in host infection.
authors: Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors: Yuan-yuan
authors: YY
authors: Sun
authors: Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China. Electronic address: lsun@qdio.ac.cn.
authors: Li
authors: L
authors: Sun
mesh_terms: D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism; D005393:Fish Diseases / Q000382:microbiology*; D005412:Flatfishes; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics / Q000502:physiology*; D055786:Gene Knockout Techniques; D006419:Heme Oxygenase (Decyclizing) / Q000235:genetics; D054884:Host-Pathogen Interactions; D007501:Iron / Q000378:metabolism; D035925:Iron-Regulatory Proteins / Q000378:metabolism*; D040901:Proteomics; D011552:Pseudomonas Infections / Q000378:metabolism / Q000662:veterinary*; D011551:Pseudomonas fluorescens / Q000378:metabolism / Q000472:pathogenicity*; D011956:Receptors, Cell Surface / Q000378:metabolism; D057057:Serine Proteases / Q000235:genetics; D013482:Superoxide Dismutase / Q000235:genetics; D014774:Virulence
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D035925:Iron-Regulatory Proteins; D011956:Receptors, Cell Surface; C029489:enterobactin receptor; D007501:Iron; D006419:Heme Oxygenase (Decyclizing); D013482:Superoxide Dismutase; D057057:Serine Proteases
keywords: Immunoprotection; Iron; Proteomic; Pseudomonas fluorescens; Virulence