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Effect of point mutations on the toxicity of shiga toxin A1 subunit
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Narwankar, Revati. Effect of point mutations on the toxicity of shiga toxin A1 subunit. Retrieved from https://doi.org/doi:10.7282/t3-n7wj-6m95

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TitleEffect of point mutations on the toxicity of shiga toxin A1 subunit
NameNarwankar, Revati (author); Tumer, Nilgun E (chair); Schaffner, Donald W (internal member); Matthews, Karl R (internal member); Rutgers University; School of Graduate Studies
Date Created2019
Other Date2019-10 (degree)
SubjectFood Science, E. coli, Escherichia coli -- Toxicology -- Genetic aspects
Extent1 online resource (vi, 39 pages) : illustrations
DescriptionShiga toxin (Stx)-producing Escherichia coli (STEC) infections can lead to life- threatening complications, including hemorrhagic colitis (HC) and hemolytic-uremic syndrome (HUS), which is the most common cause of acute renal failure in children in the United States. Previous studies have shown that STEC strains producing Stx2 are more commonly associated with HUS than those producing Stx1. Our lab has shown that the A1 subunit of Stx2 (Stx2A1) is more active than the A1 subunit of Stx1 (Stx1A1). The purpose of my study is to understand the basis for the higher toxicity of Stx2A1 by interchanging its residues with Stx1A1. Initially, the activity of wild type Stx1A1 and Stx2A1 was compared in yeast in order to establish a base line to study the effect of new mutations. We used site directed mutagenesis to exchange residues that contribute to surface charge differences between Stx1A1 and Stx2A1. Point mutations were made by interchanging Stx2A1 residues with Stx1A1 residues. If these residues contributed to the higher toxicity of Stx2A1 its toxicity would be reduced and the toxicity of Stx1A1 would be increased. The plasmids containing the mutants were transformed into yeast. The transformants were then grown in dextrose in a double overnight culture and expression was induced in galactose. The depurination activity and cytotoxicity of the point mutants was examined at different time points post-induction. Only small differences were observed between the single point mutants and the wild type toxins in both depurination activity and cytotoxicity. In contrast, several multiple mutations increased the toxicity of Stx1A1. While double mutations did not reduce the toxicity of Stx2A1 possibly due to its higher toxicity, quadruple and quintuple mutations reduced the toxicity of Stx2.
NoteM.S.
NoteIncludes bibliographical references
Genretheses, ETD graduate
Persistent URLhttps://doi.org/doi:10.7282/t3-n7wj-6m95
LanguageEnglish
CollectionSchool of Graduate Studies Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.
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