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DNA sequences proximal to human mitochondrial DNA deletion breakpoints prevalent in human disease form G-quadruplexes, a class of DNA structures inefficiently unwound by the mitochondrial replicative Twinkle helicase.

Title: DNA sequences proximal to human mitochondrial DNA deletion breakpoints prevalent in human disease form G-quadruplexes, a class of DNA structures inefficiently unwound by the mitochondrial replicative Twinkle helicase.
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Name(s): Bharti, Sanjay Kumar, author
Sommers, Joshua A, author
Zhou, Jun, author
Kaplan, Daniel L, author
Spelbrink, Johannes N, author
Mergny, Jean-Louis, author
Brosh, Robert M, author
Type of Resource: text
Genre: Journal Article
Text
Date Issued: 2014-10-24
Physical Form: computer
online resource
Extent: 1 online resource
Language(s): English
Abstract/Description: Mitochondrial DNA deletions are prominent in human genetic disorders, cancer, and aging. It is thought that stalling of the mitochondrial replication machinery during DNA synthesis is a prominent source of mitochondrial genome instability; however, the precise molecular determinants of defective mitochondrial replication are not well understood. In this work, we performed a computational analysis of the human mitochondrial genome using the "Pattern Finder" G-quadruplex (G4) predictor algorithm to assess whether G4-forming sequences reside in close proximity (within 20 base pairs) to known mitochondrial DNA deletion breakpoints. We then used this information to map G4P sequences with deletions characteristic of representative mitochondrial genetic disorders and also those identified in various cancers and aging. Circular dichroism and UV spectral analysis demonstrated that mitochondrial G-rich sequences near deletion breakpoints prevalent in human disease form G-quadruplex DNA structures. A biochemical analysis of purified recombinant human Twinkle protein (gene product of c10orf2) showed that the mitochondrial replicative helicase inefficiently unwinds well characterized intermolecular and intramolecular G-quadruplex DNA substrates, as well as a unimolecular G4 substrate derived from a mitochondrial sequence that nests a deletion breakpoint described in human renal cell carcinoma. Although G4 has been implicated in the initiation of mitochondrial DNA replication, our current findings suggest that mitochondrial G-quadruplexes are also likely to be a source of instability for the mitochondrial genome by perturbing the normal progression of the mitochondrial replication machinery, including DNA unwinding by Twinkle helicase.
Identifier: FSU_pmch_25193669 (IID), 10.1074/jbc.M114.567073 (DOI), PMC4208006 (PMCID), 25193669 (RID), 25193669 (EID), M114.567073 (PII)
Keywords: DNA Helicase, DNA Replication, G-quadruplex, Genetic Disease, Genomic Instability, Mitochondria, Twinkle
Publication Note: This NIH-funded author manuscript originally appeared in PubMed Central at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4208006.
Subject(s): Aging/genetics
Animals
Base Sequence
Circular Dichroism
Computational Biology
Conserved Sequence/genetics
DNA Damage
DNA Helicases/metabolism
DNA Replication
DNA, Mitochondrial/genetics
Disease/genetics
Evolution, Molecular
G-Quadruplexes
Genome, Mitochondrial/genetics
Humans
Mitochondria/enzymology
Mitochondrial Proteins/metabolism
Molecular Sequence Data
Neoplasms/genetics
Nucleic Acid Denaturation
Nucleotide Motifs/genetics
Recombinant Proteins/isolation & purification
Recombinant Proteins/metabolism
Sequence Deletion/genetics
Substrate Specificity
Telomere/metabolism
Ultraviolet Rays
Persistent Link to This Record: http://purl.flvc.org/fsu/fd/FSU_pmch_25193669
Owner Institution: FSU
Is Part Of: The Journal of biological chemistry.
1083-351X
Issue: iss. 43, vol. 289

Choose the citation style.
Bharti, S. K., Sommers, J. A., Zhou, J., Kaplan, D. L., Spelbrink, J. N., Mergny, J. -L., & Brosh, R. M. (2014). DNA sequences proximal to human mitochondrial DNA deletion breakpoints prevalent in human disease form G-quadruplexes, a class of DNA structures inefficiently unwound by the mitochondrial replicative Twinkle helicase. The Journal Of Biological Chemistry. Retrieved from http://purl.flvc.org/fsu/fd/FSU_pmch_25193669