Identification and Potential Use of an Aptamer for the HA-33 Protein of C. botulinum

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. 


Center for Disease Control and Prevention (2010). “Botulism”. Retrieved from

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

Click here to view full Proposal
Click here to view Progress Report 1
Click here to view Progress Report 2
Click here to view the Final Manuscript

No comments: