Structural features affecting trafficking, processing, and secretion of Trypanosoma cruzi mucins

Area of Science:

• Parasitology
• Molecular Biology
• Glycobiology

Background:

• Trypanosoma cruzi utilizes mucin-type molecules (TcSMUG, TcMUC) for protection and virulence.
• These molecules are expressed in distinct parasite life stages.

Purpose of the Study:

• To investigate the role of post-translational modifications in the trafficking of T. cruzi mucins.
• To understand the biosynthetic pathways of TcSMUG and TcMUC mucins.

Main Methods:

• In vivo tracing of tagged mucin variants in transfected epimastigotes.
• Characterization of mucin processing and secretion.
• Analysis of glycosylation patterns and functional domains.

Main Results:

• The N-terminal signal peptide targets mucins to the ER.
• The GPI-anchor is essential for forward transport along the secretory pathway.
• Secreted mucins exhibit mature O-glycosylation and specific epitopes, unlike ER-accumulated variants.
• N-glycosylation is not essential for mucin maturation and secretion.
• TcMUC and TcSMUG mucins share conserved trafficking signals but are processed by distinct glycosyltransferases.

Conclusions:

• The GPI-anchor acts as a key trafficking signal for T. cruzi mucins.
• Conserved molecular trafficking mechanisms exist between mucin families.
• Stage-specific glycosyltransferases dictate differential processing of mucins.
• These findings elucidate biosynthetic aspects of T. cruzi mucins, crucial for parasite survival and virulence.