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Updated: Mar 30, 2026
Simultaneous Mapping and Quantitation of Ribonucleotides in Human Mitochondrial DNA
Published on: November 14, 2017
Purification and Comparative Assay of the Human Mitochondrial Replicative DNA Helicase
Fernando A Rosado-Ruiz1, Minyoung So1, Laurie S Kaguni2,3
1Department of Biochemistry and Molecular Biology, Center for Mitochondrial Science and Medicine, Michigan State University, East Lansing, MI, 48824, USA.
Abstract:
The replicative mitochondrial DNA (mtDNA) helicase is essential for mtDNA replication and maintenance of the mitochondrial genome. Despite substantial advances that have been made in its characterization, there is still much to be understood about the functional roles of its domains and its interactions with the other components of the minimal mitochondrial DNA replisome. Critical to achieving this is the ability to isolate the enzyme in a stable, active form. In this chapter we describe a modified, streamlined purification strategy for recombinant forms of the enzyme. We also present assays to assess its helix unwinding activity and the stimulatory effects of the mitochondrial single-stranded DNA-binding protein (mtSSB). Finally, we describe a concentration/buffer exchange method that we have employed to achieve greater enzyme stability and appropriate conditions for biochemical and biophysical studies.
Insights
Researchers developed a streamlined purification strategy for the mitochondrial DNA (mtDNA) helicase, enabling stable, active enzyme isolation. Assays were created to study its unwinding activity and interactions with mitochondrial single-stranded DNA-binding protein (mtSSB).
Area of Science:
- Molecular Biology
- Biochemistry
- Genetics
Background:
- The replicative mitochondrial DNA (mtDNA) helicase is crucial for mtDNA replication and genome maintenance.
- Understanding its functional domains and interactions within the mtDNA replisome requires stable, active enzyme preparations.
Purpose of the Study:
- To describe a streamlined purification strategy for recombinant mtDNA helicase.
- To present assays for assessing helix unwinding activity and mtSSB stimulation.
- To detail a method for enhancing enzyme stability for biochemical and biophysical studies.
Main Methods:
- Modified, streamlined purification of recombinant mtDNA helicase.
- Development of helix unwinding assays.
- Assessment of stimulatory effects of mitochondrial single-stranded DNA-binding protein (mtSSB).
- Concentration and buffer exchange for enzyme stabilization.
Main Results:
- A reproducible method for obtaining stable, active recombinant mtDNA helicase was established.
- Assays successfully measured helicase activity and mtSSB stimulation.
- The described method improved enzyme stability for downstream studies.
Conclusions:
- The developed purification and stabilization strategy facilitates further investigation of mtDNA helicase function.
- This work provides essential tools for studying the mitochondrial DNA replisome.
- Enhanced enzyme stability is key for detailed biochemical and biophysical analyses.
