Biochemical and Structural Studies of RNA Modification and Repair
Chan, Chio Mui
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https://hdl.handle.net/2142/84868
Description
Title
Biochemical and Structural Studies of RNA Modification and Repair
Author(s)
Chan, Chio Mui
Issue Date
2009
Doctoral Committee Chair(s)
Huang, Raven H.
Department of Study
Biochemistry
Discipline
Biochemistry
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Chemistry, Biochemistry
Language
eng
Abstract
"""RNA Repair"" is a mechanism that rectifies purposeful breaks in tRNAs and mRNAs occurred during RNA processing and under cellular stress. To date, only two repair-like and repair pathways have been identified: yeast-type and phage-type, respectively. In our studies, we identified a bacterial RNA repair system composed of bacterial Pnkp and Hen1. Hen1 and Pnkp appeared pair-wise in the same operon in 39 of 934 bacterial species. Pnkp has been shown to have kinase, phosphatase, and adenylyltransferase activities, which are hallmarks of RNA repair. However, Pnkp alone is not sufficient for ligation. Pnkp/Hen1 was shown to form a tetramer during purification in size exclusion gel filtration. I carried out biochemical assays to show that AvPnkp/ AvHen1 (from A.variabilis) heterotetramer possessed ligation activity. We concluded that AvPnkp/AvHen1 belonged to a novel RNA repair and modification system. AvPnkp/ AvHen1 not only repairs tRNAAsp and tRNAArg cleaved by ribotoxins colicin E5 and colicin D, respectively, but also adds a methyl group to the same 2'OH group, which acts as a nucleophile during RNA cleavage by the ribotoxins. As a result, the repaired tRNAs resist the re-attack by ribotoxins. This repair and modification system may provide an effective mechanism to defend bacteria itself from virus infection, and also has potential therapeutic applications to reduce the cell damage caused by cancer drugs. (Abstract shortened by UMI.)."
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