An anionic synthetic sugar containing 6-SO3-NAcGlc mimics the sulfated cruzipain epitope that plays a central role in immune recognition

A.S. COUTO; L.L SOPRANO; M. LANDONI; M. POURCELOT; D.M. ACOSTA; L. BULTEL; J. PARENTE; M. R. FERRERO; M. BARBIER; C. DUSSOUY; M. I. ESTEVA; J. KOVENSKY ; V G. DUSCHAK

FEBS JOURNAL

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2012

1742-464X

Cruzipain, the major cysteine proteinase of Trypanosoma cruzi, is a glycoprotein thatcontains sulfated high-mannose type oligosaccharides. We have previously determinedthat these sulfate groups are targets of specific immune responses. In order to evaluatethe structural requirements for antibody recognition of Cz, a systematic structureactivitystudy of the chemical characteristics needed for antibody binding to the Czsulfated epitope was performed by immunoassays. To this aim, different synthesizedmolecules were coupled to the proteins BSA and aprotinin and confronted with (i) micesera specific for Cz and its C-Terminal domain (ii) antibodies raised in rabbitsimmunized with Cz and C-T and (iii) IgGs purified from human Chagas disease sera.Our results indicate that a glucosamine containing an esterifying sulfate group inposition O-6 and an N-acetyl group was the preferred epitope for the immunerecognition of sera specific for Cz and its C-T domain. Although in a minor extent,other anionic compounds bearing sulfate groups in different position and number aswell as different anionic charged groups including carboxylated or phosphorylatedmono, di and oligosaccharides were recognized. In conclusion, we found that syntheticanionic sugar conjugates containing GlcNAc6S competitively inhibit the binding ofaffinity purified rabbit anti-CT IgG to the C-terminal extension of Cz. Extending thesefindings to the context of natural infection, immune assays performed with Chagasdisease serum confirmed that the structure of synthetic GlcNAc6S mimics the Nglycan-linked sulfated epitope displayed in the C-T domain of cruzipain.