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Bacalia, Karen: Understanding Differential Ribosomal Interactions of Shiga Toxins via Analysis of Surface Charge Differences

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Title: Understanding Differential Ribosomal Interactions of Shiga Toxins via Analysis of Surface Charge Differences

Name: Karen Bacalia

Home Institute: University of Guam

Programs: RISE program

Other contributors: Jenna Abyad

Abstract: Shiga toxin (Stx)-producing Escherichia coli (STEC) produces virulent factors, Stx1 and Stx2, which can cause life threatening complications such as hemorrhagic colitis (HC) and hemolytic-uremic syndrome (HUS). HUS is the most common cause of acute renal failure in children in the United States. Epidemiological studies suggest that Stx2 has higher toxicity and is more frequently associated with HUS than Stx1. Both Stx1 and Stx2 are composed of an enzymatically active A1 subunit connected to a small A2 fragment, with five receptor binding B subunits. My lab is interested in understanding the A1 subunit as it binds to ribosomes and inhibits translation. It was found that the A1 subunit of Stx interacts with the ribosome via electrostatic interactions. It has been recently established that Stx2A1 has higher affinity for the ribosome compared to Stx1A1. However, residues on the active site and distal face of the active site do not fully account for this. Further studies are needed to determine what other electrostatic surface charge differences truly contribute to this. My project aims to identify these other residues using the software Pymol by Schrödinger. It was found that there are potential residues that can be examined experimentally. This research provides additional knowledge that could aid in development of inhibitors for STEC infection.

Biography: My name is Karen Bacalia, and I am a senior at the University of Guam studying Chemistry and Agriculture Nutrition and Food Science. My goal is to attend graduate school and study Microbiology and/or Food Science so that I can one day come back to my island and share my knowledge through coordinating with community programs or improving nutrition education in schools and my University. When I’m not studying, I enjoy baking, running, free diving, and hiking with my friends.