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The single dynamin family protein in the primitive protozoan Giardia lamblia is essential for stage conversion and endocytic transport


Gaechter, V; Schraner, E M; Willi, P; Hehl, A B (2008). The single dynamin family protein in the primitive protozoan Giardia lamblia is essential for stage conversion and endocytic transport. Traffic, 9(1):57-71.

Abstract

Dynamins are universally conserved large guanosine triphosphatases,
which function as mechanoenzymes in
membrane scission. The primitive protozoan Giardia lamblia
has a single dynamin-related protein (GlDRP) with an
unusual domain structure. Giardia lacks a Golgi apparatus
but generates transient Golgi-like delay compartments
dubbed encystation-specific vesicles (ESVs), which serve
to accumulate and mature cyst wall proteins during differentiation
to infectious cyst forms. Here, we analyze the
function of GlDRP during growth and encystation and
demonstrate that it relocalizes from peripheral endosomal–
lysosomal compartments to nascent ESVs. We show
that GlDRP is necessary for secretion of the cyst wall
material and ESV homeostasis. Expression of a dominantnegative
GlDRP variant does not interfere with ESV formation
but blocks cyst formation completely prior to regulated
exocytosis. GlDRP colocalizes with clathrin at the cell
periphery and is necessary for endocytosis of surface proteins
to endosomal–lysosomal organelles in trophozoites.
Electron microscopy and live cell imaging reveal gross
morphological changes as well as functional impairment
of the endocytic system in cells expressing the dominantnegative
GlDRP. Thus, giardial DRP plays a key role in two
distinct trafficking pathways and in organelle homeostasis,
both essential functions for the proliferation of the parasite
in the gut and its transmission to a new host.

Dynamins are universally conserved large guanosine triphosphatases,
which function as mechanoenzymes in
membrane scission. The primitive protozoan Giardia lamblia
has a single dynamin-related protein (GlDRP) with an
unusual domain structure. Giardia lacks a Golgi apparatus
but generates transient Golgi-like delay compartments
dubbed encystation-specific vesicles (ESVs), which serve
to accumulate and mature cyst wall proteins during differentiation
to infectious cyst forms. Here, we analyze the
function of GlDRP during growth and encystation and
demonstrate that it relocalizes from peripheral endosomal–
lysosomal compartments to nascent ESVs. We show
that GlDRP is necessary for secretion of the cyst wall
material and ESV homeostasis. Expression of a dominantnegative
GlDRP variant does not interfere with ESV formation
but blocks cyst formation completely prior to regulated
exocytosis. GlDRP colocalizes with clathrin at the cell
periphery and is necessary for endocytosis of surface proteins
to endosomal–lysosomal organelles in trophozoites.
Electron microscopy and live cell imaging reveal gross
morphological changes as well as functional impairment
of the endocytic system in cells expressing the dominantnegative
GlDRP. Thus, giardial DRP plays a key role in two
distinct trafficking pathways and in organelle homeostasis,
both essential functions for the proliferation of the parasite
in the gut and its transmission to a new host.

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30 citations in Scopus®
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Additional indexing

Item Type:Journal Article, not refereed, original work
Communities & Collections:05 Vetsuisse Faculty > Institute of Veterinary Anatomy
05 Vetsuisse Faculty > Institute of Parasitology
04 Faculty of Medicine > Institute of Parasitology
Dewey Decimal Classification:570 Life sciences; biology
610 Medicine & health
600 Technology
Date:2008
Deposited On:09 Feb 2009 13:44
Last Modified:05 Apr 2016 12:58
Publisher:Wiley-Blackwell
ISSN:1398-9219
Publisher DOI:10.1111/j.1600-0854.2007.00657.x
Permanent URL: http://doi.org/10.5167/uzh-12770

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