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C H A P T E R
10
Trypanosomatid surface and
secreted carbohydrates
Salvatore J. Turco
Department of Biochemistry, University of Kentucky Medical Center,
Lexington, KY, USA
INTRODUCTION
Trypanosomatid parasites have evolved unique
lifestyles, shuttling between their insect
vectors and vertebrate hosts, encountering
extremely inhospitable environments specifically
designed to keep such microbial intruders
in check. Their survival tactics often involve
glycoconjugates that form a protective obstacle
against unwelcoming forces. A general trait of
the parasite’s cell surface architecture is an
intricate and often highly structured glycocalyx
that allows the parasite to interact with and
respond to its external environment.
From the variant surface glycoprotein (VSG)
of Trypanosoma brucei and the surface mucins
of Trypanosoma cruzi to the various phosphoglycans
of Leishmania, these glycoconjugates
are obligatory for parasite survival and
virulence. The variety of the glycoconjugate
structures and, accordingly, the array of functions
that have been attributed to these molecules,
from host cell invasion to deception of
the host’s immune system, are simply amazing.
Also remarkable is the observation of parallels
and similarities in structure that underscore
evolutionary relationships between the
various parasites. For example, while the main
mechanism used for membrane protein and
polysaccharide anchorage in the trypanosomatids
is the glycosylphosphatidyl inositol (GPI)
anchor, the roles of the anchor are diverse and
parasite-specific.
In this chapter the structures and functions
of the major glycoconjugates of trypanosomatid
parasites are highlighted. However, the structures
of GPI anchors are only briefly detailed,
since several excellent reviews have been published
on the subject, nor will the biosynthetic
pathways be extensively outlined.
Molecular Medical Parasitology
ISBN 0–12–473346–8
225
Copyright © 2003 Elsevier Science Ltd.
All rights of reproduction in any form reserved.