Evidence for Conformational Mechanism on the Binding of TgMIC4 with beta-Galactose-Containing Carbohydrate Ligand

Author(s)

Santos, Adriano ^[1] ; Carvalho, Fernanda C. ^[1] ; Roque-Barreira, Maria-Cristina ^[2] ; Zorzetto-Fernandes, Andre Luiz ^[2] ; Gimenez-Romero, David ^[3] ; Monzo, Isidro ^[3] ; Bueno, Paulo R. ^[1]

Affiliation

^[1] Univ Estadual Paulista, Sao Paulo State Univ, Nanob Lab, Inst Chem, Phys Chem Dept, BR-14800060 Araraquara, SP - Brazil

^[2] Univ Sao Paulo, Fac Med Ribeirao Preto, Dept Biol Celular & Mol & Bioagentes Patogen, BR-14049900 Ribeirao Preto, SP - Brazil

^[3] Univ Valencia, Fac Quim, Dept Quim Fis, E-46100 Valencia - Spain

• Document type: Journal article
• Source: Langmuir; v. 31, n. 44, p. 12111-12119, NOV 10 2015.
• Web of Science Citations: 1

Abstract

A deeper understanding of the role of sialic/desialylated groups during TgMIC4-glycoproteins interactions has importance to better clarify the odd process of host cell invasion by members of the apicomplexan phylum. Within this context, we evaluated the interaction established by recombinant TgMIC4 (the whole molecule) with sialylated (bovine fetuin) and desialylated (asialofetuin) glycoproteins by using functionalized quartz crystal microbalance with dissipation monitoring (QCM-D). A suitable receptive surface containing recombinant TgMIC4 for monitoring beta-galactose-containing carbohydrate ligand (limit of quantification similar to 40 mu M) was designed and used as biomolecular recognition platform to study the binding and conformational mechanisms of TgMIC4 during the interaction with glycoprotein containing (fetuin), or not, terminal sialic group (asialofetuin). It was inferred that the binding/interaction monitoring depends on the presence/absence of sialic groups in target protein and is possible to be differentiated through a slower binding kinetic step using QCM-D approach (which we are inferring to be thus associated with beta-galactose ligand). This slower binding/interaction step is likely supposed (from mechanical energetic analysis obtained in QCM-D measurements) to be involved with Toxoplasma gondii (the causative agent of toxoplasmosis) parasitic invasion accompanied by ligand (galactose) induced binding conformational change (i.e., cell internalization process can be additionally dependent on structural conformational changes, controlled by the absence of sialic groups and to the specific binding with galactose), in addition to TgMIC4-glycoprotein solely recognition binding process. (AU)

• FAPESP's process: 13/04088-0 - Lectin from pathogens
• Grantee: Maria Cristina Roque Antunes Barreira
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 09/11520-0 - STUDY OF THE AFINITY OF MIC1 E MIC4 PROTEIN OF TOXOPLASMA GONDII WITH CARBOHIDRATES USING ELECTROCHEMICAL AND ELECTROGRAVIMETRICAL TECHNIQUES.
• Grantee: Adriano dos Santos
• Support Opportunities: Scholarships in Brazil - Master