Related Experiment Video

Updated: Aug 29, 2026

Application of Stopped-flow Kinetics Methods to Investigate the Mechanism of Action of a DNA Repair Protein
11:01

Application of Stopped-flow Kinetics Methods to Investigate the Mechanism of Action of a DNA Repair Protein

Published on: March 31, 2010

Physiological and biochemical defects in functional interactions of mitochondrial DNA polymerase and DNA-binding

Carol L Farr1, Yuichi Matsushima, Anthony T Lagina

  • 1Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824-1319, USA.

The Journal of Biological Chemistry
|February 3, 2004
PubMed

Insights

Mitochondrial single-stranded DNA-binding protein (mtSSB) is crucial for mitochondrial DNA synthesis and stability. Impaired mtSSB function leads to mitochondrial DNA depletion and growth defects, highlighting its role in cellular health.

Area of Science:

  • Molecular Biology
  • Genetics
  • Biochemistry

Background:

  • Mitochondrial DNA polymerase (pol gamma) activity is enhanced by mitochondrial single-stranded DNA-binding protein (mtSSB) in Drosophila embryos.
  • This interaction is vital for primer recognition, binding, and DNA strand initiation.

Purpose of the Study:

  • To investigate the role of mtSSB's DNA-binding activity in stimulating pol gamma.
  • To explore the consequences of mtSSB deficiency and functional impairment on cell growth and mitochondrial DNA (mtDNA) levels.
  • To establish Drosophila as a model for studying human mtDNA depletion syndromes.

Main Methods:

  • RNA interference (RNAi) to knock down mtSSB expression in Schneider cells.
  • Overexpression of wild-type and DNA-binding mutant mtSSB.
  • Analysis of cell growth rates and mtDNA copy numbers.

Main Results:

  • DNA-binding mutants of mtSSB failed to stimulate DNA synthesis by pol gamma.
  • RNAi-mediated mtSSB knock-down resulted in severe growth defects and mtDNA depletion.
  • Overexpression of wild-type mtSSB rescued cell growth and restored mtDNA copy number, while mutant mtSSB did not.

Conclusions:

  • mtSSB's DNA-binding capability is essential for its function in stimulating pol gamma and maintaining mtDNA stability.
  • Drosophila models with manipulated mtDNA depletion can provide insights into human mtDNA depletion syndromes and potential interventions.

More Related Videos

Proofreading and DNA Repair Assay Using Single Nucleotide Extension and MALDI-TOF Mass Spectrometry Analysis11:08

Proofreading and DNA Repair Assay Using Single Nucleotide Extension and MALDI-TOF Mass Spectrometry Analysis

Published on: June 19, 2018

Related Concept Videos

Mismatch Repair01:48

Mismatch Repair

Organisms are capable of detecting and fixing nucleotide mismatches that occur during DNA replication. This sophisticated process requires identifying the new strand and replacing the erroneous bases with correct nucleotides. Mismatch repair is coordinated by many proteins in both prokaryotes and eukaryotes.The Mutator Protein Family Plays a Key Role in DNA Mismatch RepairThe human genome has more than 3 billion base pairs of DNA per cell. Prior to cell division, that vast amount of genetic...
Mismatch Repair01:20

Mismatch Repair

Organisms are capable of detecting and fixing nucleotide mismatches that occur during DNA replication. This sophisticated process requires identifying the new strand and replacing the erroneous bases with correct nucleotides. Mismatch repair is coordinated by many proteins in both prokaryotes and eukaryotes.
The Mutator Protein Family Plays a Key Role in DNA Mismatch Repair
The human genome has more than 3 billion base pairs of DNA per cell. Prior to cell division, that vast amount of genetic...
Translesion DNA Polymerases02:10

Translesion DNA Polymerases

Translesion (TLS) polymerases rescue stalled DNA polymerases at sites of damaged bases by replacing the replicative polymerase and installing a nucleotide across the damaged site. Doing so, TLS allows additional time for the cell to repair the damage before resuming regular DNA replication.
TLS polymerases are found in all three domains of life - archaea, bacteria, and eukaryotes. Of the different classes of TLS polymerases, members of the Y family are fitted with specialized structures that...
Proofreading01:31

Proofreading

Synthesis of new DNA molecules is carried out by the enzyme DNA polymerase, which adds nucleotides on the daughter strand complementary to the template DNA strand. DNA polymerase has a higher affinity to add the correct base and ensures fidelity during DNA replication. Furthermore,  it exhibits proofreading activity during replication, using an exonuclease domain that cuts off incorrect nucleotides from the nascent DNA strand.
Errors During Replication are Corrected by the DNA Polymerase Enzyme
Proofreading01:43

Proofreading

Synthesis of new DNA molecules starts when DNA polymerase links nucleotides together in a sequence that is complementary to the template DNA strand. DNA polymerase has a higher affinity for the correct base to ensure fidelity in DNA replication. The DNA polymerase furthermore proofreads during replication, using an exonuclease domain that cuts off incorrect nucleotides from the nascent DNA strand.Errors during Replication Are Corrected by the DNA Polymerase EnzymeGenomic DNA is synthesized in...
Single-Strand DNA Binding Proteins01:03

Single-Strand DNA Binding Proteins

For successful DNA replication, the unwinding of double-stranded DNA must be accompanied by stabilization and protection of the separated single strands of the DNA. This crucial task is performed by single-strand DNA-binding (SSB) proteins. They bind to the DNA in a sequence-independent manner, which means that the nitrogenous bases of the DNA need not be present in a specific order for binding of SSB proteins to it. The binding of SSB proteins straightens single-stranded DNA (ssDNA) and makes...