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A Novel Saturation Mutagenesis Approach: Single Step Characterization of Regulatory Protein Binding Sites in RNA Using Phosphorothioates
Published on: August 21, 2018
Phosphorothioate DNA as an antioxidant in bacteria
Xinqiang Xie1, Jingdan Liang, Tianning Pu
1State Key Laboratory of Microbial Metabolism and School of Life Science and Biotechnology, Shanghai Jiaotong University, Shanghai 200030, People's Republic of China.
Nucleic Acids Research
|July 10, 2012
Summary
Bacteria protect their DNA from hydrogen peroxide (H(2)O(2)) damage using sulfur modification (phosphorothioation). This DNA phosphorothioation acts as a shield, preventing harmful breaks and allowing bacteria to survive oxidative stress.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- Diverse bacteria possess DNA with sulfur incorporated into the DNA backbone, a modification known as phosphorothioation.
- Phosphorothioate (PT) DNA can undergo oxidation by agents like hydrogen peroxide (H(2)O(2)), leading to either backbone cleavage or sulfur removal and DNA restoration.
Purpose of the Study:
- To investigate the physiological relevance of the redox reaction involving PT DNA and H(2)O(2) in bacteria.
- To determine if DNA phosphorothioation confers resistance to H(2)O(2) in vivo.
- To elucidate the protective mechanism of PT DNA against oxidative damage.
Main Methods:
- Challenging PT DNA-hosting Salmonella enterica cells with H(2)O(2).
- Assessing bacterial growth inhibition in response to H(2)O(2).
- Inactivating dnd genes essential for phosphorothioation and observing the effect on H(2)O(2) resistance.
- Analyzing DNA integrity and sulfur content in bacteria exposed to H(2)O(2).
Main Results:
- DNA phosphorothioation correlated with increased resistance to H(2)O(2)-induced growth inhibition.
- Inactivation of dnd genes abolished this resistance.
- PT DNA exhibited greater resistance to H(2)O(2)-induced double-strand breaks compared to PT-free DNA.
- Sulfur was consumed, and DNA was converted to a PT-free state in bacteria incubated with H(2)O(2).
Conclusions:
- DNA phosphorothioation modification provides bacteria with resistance against peroxide damage.
- The modification likely endows DNA with a reducing chemical property, protecting the host cell.
- This protective mechanism explains the maintenance of DNA phosphorothioation across diverse bacterial species.
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