trans

TRYPANOSOMA CRUZI 229
Mucins
GIPLs
LPPG
Target sites for trans-sialylation reaction
Mucins
CO-EtN-PO 4
2AEP
Manα1,2Manα1,2Manα1,6Manα1,4GlcNα1,6-Inos-PO4-
Alkylacylglycerol
(epimastigotes/trypomastigotes)
Ceramide
(metacyclics)
LPPG
2AEP
6
Gal f β1,3Manα1,2Manα1,2Manα1,6Manα1,4-GlcNα1,6myo-Inos-PO 4 Ceramide
Gal f β1,3
FIGURE 10.2 Schematic representation of the surface coat of Trypanosoma cruzi. The cell surface of T. cruzi is
covered with a dense layer of mucins, GIPLs (glycosylinositolphospholipids), and LPPG (lipopeptidophosphoglycan).
The structures of the mucin anchors and the predominant LPPG species are outlined. AEP, aminoethylphosphonate;
EtN, ethanolamine; GlcN, glucosamine; Inos, inositol.
host glycoconjugates, thus accounting for
the requirement for a trans-sialidase. The
galactose-rich mucin is the acceptor for the
trans-sialylation reaction in which 2,3-linked
sialic acid residues are transferred from host
glycoconjugates by the trans-sialidase enzyme
to the terminal -galactose residues of the
T. cruzi surface mucin. Interestingly, Endotrypanum,
a trypanosomatid parasite of sloths,
also has the ability to incorporate host-derived
sialic acid into molecules on its own surface.
The complete structures of the sialic acid
acceptor O-linked oligosaccharide have been
elucidated for epimastigotes of G strain and
Y strain, and metacyclic forms of G strain. The
structures of the O-linked oligosaccharides
are conserved between the epimastigotes
and the metacyclic trypomastigotes. However,
BIOCHEMISTRY AND CELL BIOLOGY: PROTOZOA