Paracoccin, a GlcNAc-binding lectin from Paracoccidioides brasiliensis, binds to laminin and induces TNF-alpha production by macrophages.
Paracoccidioides brasiliensis components interact with host cells and can influence the pathogenesis of paracoccidioidomycosis (PCM). Among the components released by P. brasiliensis, gp 43 and a heavily glycosylated antigen with MM>160 kDa are the most recognized by serum antibodies from patients with PCM. In order to isolate the high MM glycoconjugate, we carried out affinity chromatography of a crude exoantigen preparation on immobilized jacalin. The bound fraction (JBE, jacalin binding exoantigen) consisted of a major antigen of high MM and frequently of an additional 70-kDa minor protein. This protein, designated paracoccin, exhibited selective binding to immobilized GlcNAc, a property that was used for its purification. The structural data of paracoccin obtained by mass spectrometry of tryptic peptides did not match any known protein. Anti-paracoccin serum localized the lectin on the surface of P. brasiliensis yeasts, especially in the budding regions. Paracoccin was able to interact with laminin in a dose-dependent manner. This interaction was inhibited by GlcNAc, followed by D-glucose and D-mannose, but not by D-galactose, N-acetyl-galactosamine or L-fucose. Interestingly, paracoccin induced both resident and elicited mouse peritoneal cavity macrophages to release high and persistent levels of TNF-alpha in vitro, a fact that was associated with high nitric oxide production in elicited cells. Because binding to laminin can favor yeast adhesion and invasion of host tissues, and overproduction of NO has been associated with suppression of cell immunity, paracoccin is suggested to play an important role in PCM pathogenesis.
Departamento de Biologia Celular e Molecular e Bioagentes Patogênicos, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes, 3900, CEP 14049-900, Ribeirão Preto, SP, Brazil.
Kely C
KC
Coltri
Analia S
AS
Casabona-Fortunato
Margareth L
ML
Gennari-Cardoso
Camila F
CF
Pinzan
Luciana P
LP
Ruas
Vânia S
VS
Mariano
Roberto
R
Martinez
José C
JC
Rosa
Ademilson
A
Panunto-Castelo
Maria-Cristina
MC
Roque-Barreira
D000818:Animals; D000946:Antigens, Fungal / Q000378:metabolism; D005656:Fungal Proteins / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D007797:Laminin / Q000378:metabolism*; D008264:Macrophages / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D009569:Nitric Oxide / Q000378:metabolism; D010228:Paracoccidioides / Q000166:cytology / Q000378:metabolism*; D011485:Protein Binding; D011817:Rabbits; D034781:Receptors, N-Acetylglucosamine / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis*
D000946:Antigens, Fungal; D005656:Fungal Proteins; D007797:Laminin; D008565:Membrane Proteins; D034781:Receptors, N-Acetylglucosamine; D014409:Tumor Necrosis Factor-alpha; D009569:Nitric Oxide