Author Type

Graduate Student

Date of Award

2007

Document Type

Thesis

Publication Status

Version of Record

Submission Date

October 2026

Thesis/Dissertation Advisor [Chair]

Li, Zhongwei

Abstract

Three important exoribonucleases degrading RNAs in sequence-independent manner, RNase II, RNase Rand polynucleotide phosphorylase (PNPase), were shown to protect cells against oxidative stress. This is presumably due to the function of the exoribonucleases in the removal of oxidized RNA in cells. MutT pyrophosphohydrolase .was previously reported to scavenge oxidized nucleotides 8-oxoGTP and 8-oxoGDP, prevent their incorporation into RNA. Deficiency of MutT may lead to an increase in the level of 8-oxoG in RNA, which may enhance the requirement of the RNA surveillance function of the exoribonucleases. This study focuses on the roles of the RNA-degradation exoribonucleases in the removal of oxidatively-damaged RNA in the mutT background. This work shows that mutT mutation enhances the sensitivity of the RNase mutants to hydrogen peroxide. Growth defect of the pnp mutT mutant was detected even under normal aeration, but was rescued to the level of pnp mutant under anaerobic conditions. The pnp mutT mutant shows high mutator activity observed from LacZ reporter system and high level of 8-oxoG in RNA, strongly suggest that PNPase is responsible for removing 8-oxoG containing RNAs elevated in mutT background. Additionally, genetic instability observed from the mutant lacking RNase II and MutT supports the idea that RNase II may adopt a distinct pathway to reduce deleterious effect from oxidation challenge.

Extent

104 p.

Comments

Thesis (M.S.)--Florida Atlantic University, 2007.|Thesis (M.S.)--Florida Atlantic University, 2007.

Identifier

FA00000856

Format

pdf

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