The Dps-like protein Fri of Listeria monocytogenes promotes stress tolerance and intracellular multiplication in macrophage-like cells.
Members of the ferritin-like Dps protein family are found in a number of bacterial species, where they demonstrate the potential to bind iron, and have been implicated in tolerance to oxidative stress. In this study of the food-borne pathogen Listeria monocytogenes, the fri gene encoding a Dps homologue was deleted, and, compared to wild-type cells, it was found that the resulting mutant was less resistant to hydrogen peroxide, and demonstrated reduced survival following long-term (7-11 days) incubation in laboratory media. In view of this, it is shown that fri gene expression is controlled by the hydrogen peroxide regulator PerR, as well as the general stress sigma factor sigmaB. When fri mutant cells were transferred to iron-limiting conditions, growth was retarded relative to wild-type cells, indicating that Fri may be required for iron storage. This notion is supported by the observation that the L. monocytogenes genome appears not to encode other ferritin-like proteins. Given the role of Fri in resistance to oxidative stress, and growth under iron-limiting conditions, the ability of the fri mutant to infect mice was examined. When injected by the intraperitoneal route, the fri mutant demonstrated a reduced capacity to proliferate in the organs of infected mice relative to the wild-type, whereas when the bacteria were supplied intravenously this effect was mitigated. In addition, the mutant was impaired in its ability to survive and grow in J774.A1 mouse macrophage cells. Thus, the data suggest that Fri contributes to the ability of L. monocytogenes to survive in environments where oxidative stress and low iron availability may impede bacterial proliferation.
Olsen
Katja N
KN
Department of Veterinary Pathobiology, Royal Veterinary and Agricultural University (KVL), Stigbøjlen 4, DK-1870 Frederiksberg C, Denmark.
Larsen
Marianne H
MH
Department of Veterinary Pathobiology, Royal Veterinary and Agricultural University (KVL), Stigbøjlen 4, DK-1870 Frederiksberg C, Denmark.
Gahan
Cormac G M
CGM
Department of Microbiology and National Food Biotechnology Centre, University College Cork, Cork, Ireland.
Kallipolitis
Birgitte
B
Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark.
Wolf
Xenia A
XA
Department of Veterinary Pathobiology, Royal Veterinary and Agricultural University (KVL), Stigbøjlen 4, DK-1870 Frederiksberg C, Denmark.
Rea
Rosemary
R
Department of Microbiology and National Food Biotechnology Centre, University College Cork, Cork, Ireland.
Hill
Colin
C
Department of Microbiology and National Food Biotechnology Centre, University College Cork, Cork, Ireland.
Ingmer
Hanne
H
Department of Veterinary Pathobiology, Royal Veterinary and Agricultural University (KVL), Stigbøjlen 4, DK-1870 Frederiksberg C, Denmark.
D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005293:Ferritins / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D018869:Heat-Shock Response; D007501:Iron / Q000378:metabolism; D008089:Listeria monocytogenes / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity* / Q000502:physiology; D008264:Macrophages / Q000382:microbiology*; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C083911:DPS protein, Bacteria; D005293:Ferritins; D007501:Iron