Identification
and Potential Use of an Aptamer for the HA-33 Protein of C. botulinum
Emmanuella Egbonim
When inside a host, the rod-shaped bacteria Clostridium botulinum produces a deadly
neurotoxin that causes botulism, a rare and lethal disease. When released, the
neurotoxin binds to muscular nerve receptors in the body preventing the passage
of signals to and from the brain. Death usually occurs do to asphyxiation and
paralysis (CDC,
2011). If caught early, intravenous delivery of an antitoxin can neutralize
the circulating neurotoxin, preventing it from attacking the nervous system. HA-33
is a protein that forms one of the arms of the secreted neurotoxin complex. HA-33
helps facilitate the binding and transport of the neurotoxin to and across
epithelial cell layers (Ito, Sagane, et
al, 2011).
Finding an
aptamer for the HA-33 protein is beneficial in many ways, particularly in
screening for the disease. An aptamer that shows great affinity for the HA-33
protein could be used clinically in the diagnosing procedure for botulism,
since it is present in most forms of the neurotoxin. Diagnosing the disease
quicker means faster treatment and therefore a decreased mortality rate.
The target of
this research project is one of the proteins that make up the arms of the neurotoxin
complex, HA-33. This protein is found in most of the forms of the neurotoxin
and plays a role in infecting the host organism. An aptamer for HA-33 would
help to greatly expedite the process of diagnosing botulism, allowing more time
for treatment. The focus of this project can be outlined as follows:
Specific Aim 1: Perform multiple rounds of selection on a given pool
of RNA to generate an aptamer for HA-33 which can be modified to screen for
botulism
Studies show that the presence of the HA-33 protein in the botulism
neurotoxin helps promote faster binding and transport of the neurotoxin across
epithelial cell layers. Efficient transport of the neurotoxin leads to further
nerve cell impairment and infection. An aptamer with a great affinity for HA-33
can be used to detect the presence of the protein in the body, thereby diagnosing
the disease in an efficient way. Figure 1 summarizes these goals as follows:
 |
| Figure 1: Summary of Research Goals The goal of this research project is to use selection to identify an aptamer for HA-33 that can be modified for clinical use |
The samples of HA-33 used in
this project were expressed and purified by a member of the Ellington Lab at
the University of Texas at Austin’s College of Natural Sciences, in Austin, TX.
References:
Center for
Disease Control and Prevention (2010). “Botulism”. Retrieved from http://www.cdc.gov/botulism/
Ito, H.,
Sagane, Y., et al. “HA-33 facilitates
transport of the serotype D botulinum toxin across a rat intestinal epithelial
cell monolayer”. (2011), FEMS Immunology & Medical Microbiology, 61:
323–331.
Joseph W.
Arndt, Jenny Gu, et al. “The Structure of the Neurotoxin-associated
Protein HA33/A from Clostridium botulinum Suggests a Reoccurring β-Trefoil Fold
in the Progenitor Toxin Complex”, Journal of Molecular Biology, Volume 346,
Issue 4, 4 March 2005, Pages 1083-1093
United
States Department of Agriculture (2011). Foodborne Illness and Disease:
Clostridium botulinum Retrieved from
https://www.fsis.usda.gov/factsheets/Clostridium_botulinum/
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