Aspects of gene expression and regulation in plasmodium falciparum gametocytogenesis
Date
2006-11-14T12:02:53Z
Authors
Meyersfeld, Daniel
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Abstract
Malaria is one of the most debilitating pathogenic infections known to man,
responsible for approximately three million deaths annually, primarily children in
sub-Saharan Africa. The parasite has evaded multiple attempts at eradication,
predominantly through the complexity of its life cycle, the ability to elude host
immune response, and gametocyte formation to ensure dissemination. The recent
completion of the genome sequence has opened up a multitude of avenues for
exploration and identification of novel drug and vaccine targets, as well as providing
a glimpse into the complex mechanisms that have contributed to the success of this
pathogen. The mechanisms of gene regulation, especially those governing
gametocytogenesis, have, however, not yet been elucidated.
In this research, differential display has been used to identify some of the genes that
are differentially expressed between the asexual parasite and gametocyte stages of P.
falciparum. Numerous genes involved in diverse aspects of metabolism, protein
synthesis and immune evasion were identified. A combination of BLASTN and
BLASTX similarity searches was used to categorize and increase the confidence with
which a transcript could be identified. Expression data for confidently identified
genes were confirmed using reverse slot blot and available microarray data.
PfMyb2, a novel transcription factor which may regulate genes involved in
gametocytogenesis, was characterized. The DNA binding domains of the protein
were cloned and expressed as a histidine fusion protein. Mobility shift assays were
used to assess the in vitro binding capability of the recombinant 6xHis-PfMyb2,
which bound to oligonucleotides containing the consensus Myb regulatory element.
Two of the oligonucleotides represent sequences located within promoters of P.
falciparum genes (Pfcrk1 and Pfmap1) known to play a role in regulating the cell
cycle, a function ascribed to many members of the vertebrate Myb family. The
identification of PfMyb2 as a bona fide transcription factor is a first step into gaining
some insight into the many regulatory processes that occur during the life cycle of
this complex organism. A better understanding of the molecular mechanisms that
govern its survival is essential for the ultimate eradication of this deadly parasite.
Description
Student Number : 9503239E -
PhD thesis -
Faculty of Science
Keywords
plasnodium falciparum, gene expression, gene regulation, transcription factors