Molecular characterization of ribonucleoproteic antigens containing repeated amino acid sequences from Trypanosoma cruzi.
Trypanosoma cruzi expresses several proteins containing antigenic amino acid repeats. Here we characterized TcRpL7a and TcRBP28, which carry similar repeat motifs and share homology to the eukaryotic L7a ribosomal protein and to a Trypanosoma brucei RNA binding protein, respectively. Analyses of the full length and truncated recombinant TcRpL7a showed that the humoral response of patients with Chagas disease is directed towards its repetitive domain. Sequence analyses of distinct copies of TcRpL7a genes present in the genome of six T. cruzi strains indicate that the number of repeats is higher in proteins from T. cruzi II than T. cruzi I strains. A serum panel of 59 T. cruzi infected patients showed that 73% reacted with TcRpL7a, 71% reacted with TcRBP28 and 80% reacted with 1:1 mixture of both antigens. Synthetic peptides harboring the TcRpL7a repeat motif reacted with 46% of the serum samples. Antibodies raised against both antigens identified equivalent amounts of the native proteins in all three stages of the parasite life cycle. Analyses of subcellular fractions indicated that TcRBP28 is present in the cytoplasm whereas TcRpL7a co-fractionates with polysomes. Confirming their predicted cellular localization, GFP fusions showed that, whereas GFP::TcRBP28 localizes in the cytoplasm, GFP::TcRpL7a accumulates in the nucleus, where ribosome biogenesis occurs.
Departamento de Bioquímica e Imunologia, ICB, Universidade Federal de Minas Gerais, Avenida Antônio Carlos, Pampulha, Belo Horizonte, MG, Brazil.
Fabiano S
FS
Pais
Wanderson D
WD
DaRocha
Ramon M
RM
Almeida
Sophie Y
SY
Leclercq
Marcus L
ML
Penido
Stenio P
SP
Fragoso
Daniella C
DC
Bartholomeu
Ricardo T
RT
Gazzinelli
Santuza M R
SM
Teixeira
D000595:Amino Acid Sequence; D000818:Animals; D000913:Antibodies, Protozoan / Q000276:immunology*; D000953:Antigens, Protozoan / Q000032:analysis / Q000235:genetics / Q000276:immunology*; D001324:Autoantigens / Q000032:analysis / Q000235:genetics / Q000276:immunology*; D002467:Cell Nucleus / Q000737:chemistry; D014355:Chagas Disease / Q000276:immunology; D003593:Cytoplasm / Q000737:chemistry; D018604:Epitope Mapping; D006801:Humans; D008969:Molecular Sequence Data; D010455:Peptides / Q000276:immunology; D020449:Repetitive Sequences, Amino Acid; D016415:Sequence Alignment; D014349:Trypanosoma cruzi / Q000235:genetics / Q000276:immunology*; D055517:snRNP Core Proteins
D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D001324:Autoantigens; D010455:Peptides; D055517:snRNP Core Proteins