FbpA, a novel multifunctional Listeria monocytogenes virulence factor.
Listeria monocytogenes is a Gram-positive intracellular bacterium responsible for severe opportunistic infections in humans and animals. Signature-tagged mutagenesis (STM) was used to identify a gene named fbpA, required for efficient liver colonization of mice inoculated intravenously. FbpA was also shown to be required for intestinal and liver colonization after oral infection of transgenic mice expressing human E-cadherin. fbpA encodes a 570-amino-acid polypeptide that has strong homologies to atypical fibronectin-binding proteins. FbpA binds to immobilized human fibronectin in a dose-dependent and saturable manner and increases adherence of wild-type L. monocytogenes to HEp-2 cells in the presence of exogenous fibronectin. Despite the lack of conventional secretion/anchoring signals, FbpA is detected using an antibody generated against the recombinant FbpA protein on the bacterial surface by immunofluorescence, and in the membrane compartment by Western blot analysis of cell extracts. Strikingly, FbpA expression affects the protein levels of two virulence factors, listeriolysin O (LLO) and InlB, but not that of InlA or ActA. FbpA co-immunoprecipitates with LLO and InlB, but not with InlA or ActA. Thus, FbpA, in addition to being a fibronectin-binding protein, behaves as a chaperone or an escort protein for two important virulence factors and appears as a novel multifunctional virulence factor of L. monocytogenes.
Dramsi
S
S
Unité des Interactions Bactéries-Cellules, Institut Pasteur, 28 rue du Dr Roux, 75724 Paris, France.
Bourdichon
F
F
Cabanes
D
D
Lecuit
M
M
Fsihi
H
H
Cossart
P
P
D018829:Adhesins, Bacterial / Q000235:genetics* / Q000502:physiology; D000818:Animals; D001422:Bacterial Adhesion; D001427:Bacterial Toxins / Q000032:analysis; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D015169:Colony Count, Microbial; D004195:Disease Models, Animal; D005353:Fibronectins / Q000378:metabolism; D005798:Genes, Bacterial; D006360:Heat-Shock Proteins / Q000032:analysis; D006460:Hemolysin Proteins; D006801:Humans; D007422:Intestines / Q000382:microbiology; D008089:Listeria monocytogenes / Q000235:genetics* / Q000472:pathogenicity*; D008088:Listeriosis / Q000382:microbiology; D008099:Liver / Q000382:microbiology; D008198:Lymph Nodes / Q000382:microbiology; D008565:Membrane Proteins; D051379:Mice; D008822:Mice, Transgenic; D018832:Molecular Chaperones / Q000235:genetics / Q000502:physiology; D016254:Mutagenesis, Insertional; D016366:Open Reading Frames; D011485:Protein Binding; D017386:Sequence Homology, Amino Acid; D013154:Spleen / Q000382:microbiology; D014774:Virulence / Q000235:genetics; D037521:Virulence Factors / Q000235:genetics* / Q000302:isolation & purification*
D018829:Adhesins, Bacterial; D001427:Bacterial Toxins; D005353:Fibronectins; D006360:Heat-Shock Proteins; D006460:Hemolysin Proteins; D008565:Membrane Proteins; D018832:Molecular Chaperones; D037521:Virulence Factors; C078635:fibronectin-binding proteins, bacterial; C038705:hlyA protein, Listeria monocytogenes