title: Trypanosoma cruzi heparin-binding proteins present a flagellar membrane localization and serine proteinase activity.
abstract: Heparin-binding proteins (HBPs) play a key role in Trypanosoma cruzi-host cell interactions. HBPs recognize heparan sulfate (HS) at the host cell surface and are able to induce the cytoadherence and invasion of this parasite. Herein, we analysed the biochemical properties of the HBPs and also evaluated the expression and subcellular localization of HBPs in T. cruzi trypomastigotes. A flow cytometry analysis revealed that HBPs are highly expressed at the surface of trypomastigotes, and their peculiar localization mainly at the flagellar membrane, which is known as an important signalling domain, may enhance their binding to HS and elicit the parasite invasion. The plasmon surface resonance results demonstrated the stability of HBPs and their affinity to HS and heparin. Additionally, gelatinolytic activities of 70 kDa, 65·8 kDa and 59 kDa HBPs over a broad pH range (5·5-8·0) were revealed using a zymography assay. These proteolytic activities were sensitive to serine proteinase inhibitors, such as aprotinin and phenylmethylsulfonyl fluoride, suggesting that HBPs have the properties of trypsin-like proteinases.
authors.affiliation: Laboratório de Ultra-estrutura Celular, Instituto Oswaldo Cruz/FIOCRUZ, RJ, Brazil.
authors.forename: F O R
authors.initials: FO
authors.lastname: Oliveira
authors.forename: C R
authors.initials: CR
authors.lastname: Alves
authors.forename: F S
authors.initials: FS
authors.lastname: Silva
authors.forename: L M C
authors.initials: LM
authors.lastname: Côrtes
authors.forename: L
authors.initials: L
authors.lastname: Toma
authors.forename: R I
authors.initials: RI
authors.lastname: Bouças
authors.forename: T
authors.initials: T
authors.lastname: Aguilar
authors.forename: H B
authors.initials: HB
authors.lastname: Nader
authors.forename: M C S
authors.initials: MC
authors.lastname: Pereira
mesh_terms: D002462:Cell Membrane / Q000201:enzymology / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D005407:Flagella / Q000201:enzymology*; D005434:Flow Cytometry; D005780:Gelatin / Q000378:metabolism; D005786:Gene Expression Regulation; D006493:Heparin / Q000378:metabolism; D006790:Host-Parasite Interactions; D006863:Hydrogen-Ion Concentration; D011485:Protein Binding; D015800:Protozoan Proteins / Q000378:metabolism*; D057057:Serine Proteases / Q000378:metabolism*; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology; D014349:Trypanosoma cruzi / Q000201:enzymology / Q000502:physiology*
chemical_list: D015800:Protozoan Proteins; D015842:Serine Proteinase Inhibitors; D005780:Gelatin; D006493:Heparin; D057057:Serine Proteases