Plasmodium falciparum: Funktionelle Analyse von Proteinen des sekretorischen Transportweges in transfizierten Zellen
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Philipps-Universität Marburg
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Abstract
Plasmodium falciparum is an intracellular
parasite of red blood cells. The parasite exports various
proteins to numerous destinations inside of its plasma membrane
and beyond into the host erythrocyte. These secreted proteins
are directly related to the severe clinical symptoms of malaria
tropica. The export of most parasite proteins is inhibited in
the presence of brefeldin A (BFA). The conserved sec7 domain of
Arf-Gef (ADP-ribosylation factor - guanine nucleotide exchange
factor) is the main target of BFA. Arf-Gef proteins are
necessary to activate Arf and consequently for the formation of
COP I coated transport vesicles. Here it is shown by double
cross-over gene replacement experiments with P. falciparum that
a point mutation within the sec7 domain is sufficient to confer
BFA-resistance to parasites. Complementation studies with the
yeast S. cerevisiae in which the gea1 sec7 domain was replaced
by the P. falciparum sec7 domain including the mutation
revealed an intermediate growth phenotype. This provides
evidence that P. falciparum Arf-Gef functions as a
GDT-GTP-exchange protein in ER-/Golgi transport processes. The
sec7 region of the arf gef gene encodes an unusual long
insertion sequence. In silico modelling algorithms as well as
heterologous expression in yeast cells were used here to
examine the significance of this insertion sequence. Parasite
proteins that are transported into intra-parasitic compartments
like the apical complex or the apicoplast in many cases contain
amino-terminal ER signal sequences. Many proteins destined for
the host cell compartment contain internal hydrophobic regions
which are putative ER-signals. The internal hydrophobic region
of Gbp130 (glycophorine binding protein) and truncated versions
thereof were functionally analysed as to their ER-signal
potential in S. cerevisiae. The P. falciparum Exp-1 signal
sequence was used as a positive control. None of the plasmodial
sequences could restore ER-translocation in vivo possibly due
to parasite specific transport/ translocation processes that
could not be reconstituted in yeast cells. Two aspects of
secretory processes in P. falciparum were investigated in this
thesis. For an understanding of protein export pathways and
mechanisms it is necessary to identify and characterize more
mediator molecules involved in parasite
secretion.
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Contributors
Supervisor:
Dates
Created: 2004Issued: 2004-04-20Updated: 2011-08-10
Faculty
Fachbereich Biologie
Publisher
Philipps-Universität Marburg
Language
ger
Data types
DoctoralThesis
Keywords
ARF-GEF , sec7 domainCOPARF1ARF1brefeldin AARF-GEF , Sec7 DomäneCOP , Transportvesikeltransport vesicleBrefeldin A
DFG-subjects
Saccharomyces cerevisiae , TransfektionPlasmodium falciparumHomologe RekombinationSekretion
DDC-Numbers
570
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Wiek, Sabine (129001260): Plasmodium falciparum: Funktionelle Analyse von Proteinen des sekretorischen Transportweges in transfizierten Zellen. : Philipps-Universität Marburg 2004-04-20. DOI: https://doi.org/10.17192/z2004.0112.
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This item has been published with the following license: In Copyright